If you’ve read any of my articles here about the inner workings of CPU cores in Apple silicon chips, you’ll know I’m no stranger to using the command tool powermetrics to discover what they’re up to. Last week I attempted something more adventurous when trying to estimate how much power and energy are used in a single Visual Look Up (VLU).

My previous tests have been far simpler: start powermetrics collecting sample periods using Terminal, then run a set number of core-intensive threads in my app AsmAttic, knowing those would complete before that sampling stopped. Analysing dozens of sets of measurements of core active residency, frequency and power use is pedestrian, but there’s no doubt as to when the tests were running, nor which cores they were using.

VLU was more intricate, in that once powermetrics had started sampling, I had to double-click an image to open it in Preview, wait until its Info tool showed stars to indicate that stage was complete, open the Info window, spot the buttons that appeared on recognised objects, select one and click on it to open the Look Up window. All steps had to be completed within the 10 seconds of sampling collections, leaving me with the task of matching nearly 11,000 log entries for that interval against sampling periods in powermetrics' hundred samples.

The first problem is syncing time between the log, which gives each entry down to the microsecond, and the sampling periods. Although the latter are supposed to be 100 ms duration, in practice powermetrics is slightly slower, and most ranged between about 116 and 129 ms. As the start time of each period is only given to the nearest second, it’s impossible to know exactly when each sample was obtained.

Correlating log entries with events apparent in the time-course of power use is also tricky. Some are obvious, and the start of sampling was perhaps the easiest giveaway as powermetrics has to be run using sudo to obtain elevated privileges, which leaves unmistakeable evidence in the log. Clicks made on Preview’s tools are readily missed, though, even when you have a good estimate of the time they occurred.

Thus, the sequence of events is known with confidence, and it’s not hard to establish when VLU was occurring. As a result, estimating overall power and energy use for the whole VLU also has good confidence, although establishing finer detail is more challenging.

The final caution applies to all power measurements made using powermetrics, that those are approximate and uncalibrated. What may be reported as 40 mW could be more like 10 or 100 mW.

In the midst of this abundance of caution, one fact stands clear: VLU hardly stresses any part of an Apple silicon chip. Power used during the peak of CPU core, GPU and neural engine (ANE) activity was a small fraction of the values measured during my previous core-intensive testing. At no time did the ten P cores in my M4 Pro come close to the power used when running more than one thread of intensive floating-point arithmetic, and the GPU and ANE spent much of time twiddling their thumbs.

Yet when Apple released VLU in macOS Monterey, it hadn’t been expecting to be able to implement it at all in Intel chips because of its computational demand. What still looks like magic can now be accomplished with ease even in a base M1 model. And when we care to leave our Macs running, mediaanalysisd will plod steadily through recently saved images performing object recognition and classification to add them to Spotlight’s indexes, enabling us to search images by labels describing their contents. Further digging in Apple’s documentation reveals that VLU and indexing of discovered object types is currently limited by language to English, French, German, Italian, Spanish and Japanese.

Some time in the next week or three, when Apple releases macOS Tahoe, we’ll start seeing Apple silicon Macs stretch their wings with the first apps to use its Foundation Models. These are based on the same Large Language Models (LLMs) already used in Writing Tools, and run entirely on-device, unlike ChatGPT. This has unfortunately been eclipsed by Tahoe’s controversial redesign, but as more developers get to grips with these new AI capabilities, you should start to see increasingly novel features appearing.

What developers will do with them is currently less certain. These LLMs are capable of working with text including dialogue, thus are likely to appear early in games, and should provide specialist variants of more generic Writing Tools. They can also return numbers rather than text, and suggest and execute commands and actions that could be used in predictive automation. Unlike previous support for AI techniques such as neural networks, Foundation Models present a simple, high-level interface that can require just a few lines of code.

If you’ve got an Apple silicon Mac, there’s a lot of potential coming in Tahoe, once you’ve jiggled its settings to accommodate its new style.

One of the golden rules in narrative painting is to tell stories that the viewer is already familiar with, because of the limitations imposed by still images. By the middle of the nineteenth century, though, artists were breaking that rule in what became a new sub-genre of the ‘problem picture’, with open-ended narrative encouraging the viewer to construct their own stories. William Blake was a precursor to that in some of his paintings, and this weekend I look at two examples that try to tell stories we’re unfamiliar with.

At first sight, Blake’s painted etching The Ancient of Days from about 1821 might represent the Christian God seen as master craftsman, forming the world out of the darkness below heaven. That would be an innovative but hardly revolutionary interpretation of the opening of the book of Genesis.

That wasn’t Blake’s intention, though. This represents Urizen, one of many figures from his own mythology, and documented only in the artist’s writings. There, Urizen symbolises reason, his name most probably a semi-conscious pun on your reason. This painting shows Urizen the architect, creating the world using his compasses. He goes on to have the role of the jealous and vengeful god of the Old Testament, but his desire for dominion brings about his downfall into a state of Satan.

Representations of God as architect aren’t common, but Blake’s would be by no means unique.

This frontispiece to a Bible Moralisée from around 1220-30 shows the Christian God as architect, using his compasses during the creation of the world. The compasses continue in various modern symbols, including those that feature in freemasonry, and in its references to the Supreme Being as the Great Architect of the Universe.

Urizen typically appears with long and streaming white hair and beard, as in Blake’s plates throughout his First Book of Urizen from 1796.

But Urizen isn’t the only figure from Blake’s mythology who has long white hair and beard: above is Elohim Creating Adam from 1795, for example.

In Blake’s God Judging Adam also from about 1795, both figures sport long, flowing white hair and beards, which appear to be markers not so much of their ages or identities, but of the ancient nature of events.

Long white hair and beards are of course a long-established tradition in visual art: here is a contemporary example of Tiresias, the blind prophet of Apollo at Thebes, in Henry Fuseli’s Tiresias Appears to Ulysses During the Sacrifice (1780-85). Fuseli was Professor of Painting at the Royal Academy, and a great influence on Blake.

Characteristic of the figure of Urizen in The Ancient of Days is the unusual way in which the figure’s hair and beard stream as if in a strong wind, the figure’s nakedness, and its posture.

This can be traced most immediately to a major work by another contemporary painter who was highly influential on Blake: James Barry’s King Lear Weeping over the Dead Body of Cordelia (1786–8). Barry was also Professor of Painting at the Royal Academy, and the similarities between King Lear’s white hair and beard here, and those of Blake’s Urizen in The Ancient of Days, are striking.

Blunt found another potential source in Pellegrino Tibaldi’s figure of Neptune (1549-51) in his fresco showing the story of Ulysses in the Palazzo Poggi. Although now relatively obscure, Blake saw fresco as being ‘true’ art, and was long an enthusiast of frescos, even if he saw few. A contemporary popular book of prints of frescos included an engraving of Tibaldi’s Neptune, so this image would have been accessible to both Blake and Barry.

It’s likely that Tibaldi’s Neptune was itself a reference to Michelangelo’s earlier frescos in the Sistine Chapel: the detail above showing God creating the sun and moon, and even more important that below showing the creation of Adam (c 1511).

Blake knew both of these sections of the Sistine Chapel frescos well, having engraved them previously. They also link to Blake’s own Elohim Creating Adam above.

Blake’s Urizen the architect, seen creating the world using his compasses, is distinct from both God and Elohim in his nakedness. In Blake’s written narrative, the distinction between Urizen and Elohim becomes more blurred, when the former goes on to have the role of the jealous and vengeful god of the Old Testament, until his desire for dominion brings about his downfall.

It may be tempting to assume that, just because Blake’s paintings appear so original and different, they originate entirely from his own mind. However, Blake was just as likely to borrow from and refer to other visual art as any other master.

References

Blunt, A (1959) The Art of William Blake, Oxford UP.
Butlin, M (1981) The Paintings and Drawings of William Blake, 2 vols, Yale UP. ISBN 978 0 300 02550 7.
Damon, S Foster (2013) A Blake Dictionary, the Ideas and Symbols of William Blake, updated edn., Dartmouth College Press. ISBN 978 1 61168 443 8.
Vaughan, William (1999) William Blake, British Artists, Tate Publishing. ISBN 978 1 84976 190 1.

Here are this weekend’s Mac riddles to entertain you through family time, shopping and recreation.

1: Last edit from KeyGrip but not for the amateur.

2: Movement to accompany 1 for its titles and effects.

3: Opening that closed for your photos a decade ago.

To help you cross-check your solutions, or confuse you further, there’s a common factor between them.

I’ll post my solutions first thing on Monday morning.

Please don’t post your solutions as comments here: it spoils it for others.

Few other companies have had as much influence on the Mac and its success as Adobe. Founded just over a year before Apple launched the Mac, its original mission was to develop and market its new PostScript page description language, originally designed and written by Adobe’s co-founders, John Warnock (1940-2023) and Charles Geschke (1939-2021). Steve Jobs (1955-2011) was an early enthusiast who shared their vision. After an unsuccessful bid to buy Adobe, Apple bought a 19% stake in it and paid in advance for a five-year licence for PostScript. When Apple introduced its first PostScript laser printer, the LaserWriter, in March 1985 the partnership launched the Desktop Publishing (DTP) revolution.

Adobe Illustrator (1987)

The same year the LaserWriter brought PostScript and its fonts to the first DTP designers, Adobe started development of its first retail software product, Illustrator, released two years later in 1987. This is a vector graphics editor aimed initially at creating in Encapsulated PostScript Format (EPSF), so had to render the bézier curves of PostScript into the Mac’s QuickDraw graphics.

Illustrator wasn’t offered for Windows for another two years, and even then was widely criticised for lagging behind its Mac version. It wasn’t until 1997 that the Windows version achieved parity. Adobe’s major competitor, Aldus FreeHand, was preferred by many professionals until Adobe bought Macromedia in 2005, following which it was quietly suffocated.

This is Adobe Illustrator running in Mac OS X 10.2 Jaguar in early 2003.

Adobe Photoshop (1990)

In 1988, Adobe bought the distribution licence to a raster graphics editor already named Photoshop by its original developers, brothers Thomas and John Knoll. The first Adobe version was released for Macs only in February 1990. It has the distinction of being the major app developed using Apple’s MacApp class library, and wasn’t released for Windows until late 1992, by which time it was establishing itself as the standard, particularly for pro photographers. In 2007 it was joined by Adobe Photoshop Lightroom, an image management app that became the standard when Apple discontinued Aperture in 2015.

This is Adobe Photoshop in Mac OS 9.2, in late 2002.

And this is its matching Mac OS X version in 10.2 Jaguar.

Adobe Premiere (1991)

Digital non-linear video editing was in its infancy in 1991, when SuperMac Technology developed a QuickTime-based app to support its Video Spigot capture card. Adobe purchased the whole project, and four months later at the end of 1991 released the first version of Adobe Premiere. Although severely constrained by hardware of the time, it proved another successful Mac-only product until its Windows version was released almost two years later, and the product was renamed Adobe Premiere Pro in 2003.

In 1995, Premiere was joined by After Effects following Adobe’s acquisition of Aldus the previous year. After Effects provides digital effects including motion graphics and compositing. In 1999, Apple released Final Cut Pro, whose early development had been by the first Premiere development team working for Macromedia, and has since added Motion and other apps to form its Pro suite. They successfully competed against Adobe’s video products on the Mac.

PDF and Adobe Acrobat (1993)

I have already given a fuller account of the history of PDF and Adobe Acrobat on Macs.

This is Acrobat Distiller 4.0 running on Mac OS 9.1 in early 2001, showing some of its bewildering array of options for turning PostScript files into PDF.

Adobe provided its free Acrobat Reader for Mac OS X, here seen in 10.0 Cheetah.

Adobe FrameMaker (1995)

FrameMaker, originally developed by Frame Technology, is a high-end technical publishing system bought by Adobe in 1995. It was then offered in a premium version with extensive support for SGML, seen here in 2002, two years before Adobe dropped this Mac version.

Adobe PageMaker (1995-2001)

From its launch in 1985, the leading page layout app for Macs had been Aldus PageMaker, which Adobe acquired when it purchased Aldus in 1994. By this time, PageMaker was under increasing pressure from QuarkXPress, which had become preferred by many professionals. As a result, Aldus had already started to develop what it claimed would be its “Quark killer”, and Adobe continued that. It then discontinued support for PageMaker in a final version released in 2001, which notoriously didn’t support Mac OS X and was never ported to Intel Macs either.

Adobe InDesign (1999)

Early development on what was to become Adobe InDesign had started in Aldus before it was swallowed up by Adobe, and its first version was released in 1999, for both Windows and Mac OS. When Mac OS 10.0 Cheetah was released in March 2001, InDesign was its first native page layout app, as well as the first to support Unicode and advanced features of OpenType fonts. As QuarkXPress entered a decline, InDesign became the DTP product of choice.

This is Adobe InDesign in its early days, seen here editing Christmas cards in Mac OS X 10.2 Jaguar in December 2002.

Adobe Dreamweaver (2005)

Dreamweaver is a website development app that originated in Macromedia in 1997, and was acquired by Adobe with its purchase of that company in 2005.

Adobe Dreamweaver is seen here running in Mac OS X 10.6 Snow Leopard in August 2009.

Flash (2005-2020)

Another of Macromedia’s products that Adobe acquired in 2005 was Flash, a rich multimedia software platform that became enormously popular in websites including YouTube and many corporate sites. Flash came with its own scripting language ActionScript, but proved a security nightmare because of its long series of exploited vulnerabilities. Although Flash Player was almost universal on Macs, Apple refused to allow Flash support on its devices, leading to a bitter standoff between Steve Jobs and Adobe. About a year later, much to the relief of security staff around the world, Adobe announced it would cease Flash development; it was deprecated in 2017, and all support stopped at the end of 2020.

‘Shockwave Flash’ and the Flash Player plagued Mac OS X Tiger in 2006.

Others

There have been and still are many other apps from Adobe. One of my favourites was LaserTalk, first released by Emerald City Software in 1988. This was a PostScript debugger acquired by Adobe and bundled in its PostScript SDK. Finally, there was Adobe Streamline, a tool for converting bitmap graphics into Adobe Illustrator vector graphics, first released in 1989, and absorbed into Illustrator in about 2001. No doubt you will also have your own favourites.

Apple sold its 19% stake in Adobe in 1989, and in 2011 Adobe introduced its Creative Cloud subscription service, that two years later replaced its popular Creative Studio DVD distributions with perpetual licences.

Dice have been thrown and rolled by people throughout recorded history. Early dice were often irregular, made of bone or stone and used primarily for gambling. Although they don’t appear to have played any significant role in mythology, their role in the events of the Crucifixion is well recorded in the New Testament Gospels.

Jacopo Tintoretto’s huge and magnificent Crucifixion from 1565 depicts the biblical account of guards gambling with dice, as seen in the detail below.

On the left of this detail, two men are gambling with dice in a small rock shelter suggestive of a tomb. To the right of them, a gravedigger has just started his work with a spade.

The Christian Church has generally taken a dim view of gambling, and shunned dice. Several artists have expressed this in paint, but none so forcefully as Hieronymus Bosch.

For Bosch and his patrons, gambling was definitely one of the cardinal sins. It appears in the garden of Hell in the right panel of his magnificent Garden of Earthly Delights from about 1495-1505. In this damning conclusion, figures are mutilated and tormented in a nightmare landscape dominated by non-human creatures and alarming objects, where gambling takes the foreground.

In the foreground, a huge blue bird, wearing a cauldron on its head and swallowing a whole human, presides over the scene. Two main groups of victims here are clustered around objects associated with gaming and gambling, and those for making music, then associated with the work of the devil, and immoral activities such as dancing. Playing cards are scattered on the ground beneath an overturned gaming table, and dice are balanced precariously on an index finger and on the head of a naked woman. From among that cluster of figures, a pair of dark blue non-human arms holds high a backgammon board with three dice.

Not all cultures have been as damning, though.

Albert Anker turns to classical times to put his spin on gambling games in his Knucklebone Players (1864). Three youths are here playing a game of greater skill, but still frequently the basis of gambling. The distinguished men in the background are hardly the sort to frequent a gambling den, surely?

Nevertheless, playing with dice continued as a cardinal sign of sin.

Alcohol, and that other vice tobacco, are cited in David Teniers the Younger’s The Dice Shooters (1630-50). In common with other paintings of card-playing and gambling in this period, it’s set in a dingy room in a rough tavern. Drawing on their clay pipes and with glasses of beer in hand, a group of men are completely absorbed in gambling large stacks of coins on the throw of their dice.

William Hogarth’s successor Thomas Rowlandson painted his Gaming Table in watercolour in 1801. Players here are putting their stakes on dice, which are about to be revealed by the man at the far right of the table, who seems to have been raking the money in.

Although Gustave Courbet’s portrait of the operatic singer Louis Gueymard (1822–1880) as Robert le Diable (1857) shows the last scene in Act 1 of Giacomo Meyerbeer’s opera Robert le Diable (1831), its message is clear. In this scene, Gueymard’s character Robert gambles away his entire estate on dice; in the opera this is marked by the aria L’or est une chimère: ‘gold is but an illusion’.

Dante Gabriel Rossetti is less convinced. In his watercolour of Hesterna Rosa from 1865, he shows a moment from the contemporary play Philip van Artevelde, written by Henry Taylor in 1834. Van Artevelde was a Flemish patriot who lived between about 1340-1382, and led the Ghent rebellion in 1381, only to be crushed to death in battle the following year. In Taylor’s play, van Artevelde has a relationship with a woman of lower class; in this scene, his lover has paused to reflect on her life while he plays dice with a friend. The painting’s title means yesterday’s rose, and draws on the theme of the fallen woman, so popular with Rossetti.

Murillo’s Young Boys Playing Dice of about 1675 adopts a different theme, of gambling among the poor and vulnerable. Two scruffy urchins from the streets of Seville are throwing dice for the small piles of change which are probably their entire fortunes. A third stands over them, chewing at a bread roll while his dog looks up longingly at the food.

Create a new folder inside your Documents folder, and inspect its permissions in the Finder’s Get Info dialog. You should see that you, as the owner of that folder, have Read & Write privileges, your group staff can only read it, as can everyone. Have you ever wondered how that new folder, or any new file, gets its permissions set in that way? This article explains how, and how you can control that.

Although it might appear to be of little use, there are circumstances when it becomes really important, for example when you create folders and files in shared locations. What if you were to use a sharepoint on a NAS that you shared with several others, and created folders and files there, with those same permissions? Although your colleagues would be able to read that folder and documents, they wouldn’t be able to write to them. Instead, you’d want those to give both Read & Write privileges to everyone in your group, and that’s something you can set with your umask.

Your Mac has at least two umasks, stored in /private/var/db/com.apple.xpc.launchd/config. One for all your user processes, including the Finder and apps that you run, the other for system processes, stored in the same place. If you want to override the default umasks, then you do so using the launchctl command in Terminal. Before you can do that, you need to know how to specify those umasks using octal numbers.

Octal permissions

The most compact and convenient way to express permissions isn’t in hexadecimal, but octal, and that’s standard across all Unix-based systems. Open a file or folder in my free utility Precize, for instance, and it reports its Posix permissions as three octal digits, together with the names and ID numbers of the owner and group.

A complete set of permissions actually consists of four octal digits, but the first is used for special bits (setuid, setgid and sticky), which don’t concern us here. The next and most important three digits give the permission settings for the owner, group, and everyone else, in that order.

Each digit is the sum of up to three numbers:

• 4 means that reading is allowed
• 2 means that writing is allowed
• 1 means that a file can be executed, or a directory searched.

So the standard permissions set on that new folder you created work out thus:

• the owner has Read & Write access, and search = 4 + 2 + 1 = 7
• the group has Read only access, and search = 4 + 1 = 5
• everyone has Read only access, and search = 4 + 1 = 5

and the octal permissions of that folder are given as 755. For a shared folder where all in the group need both read and write access, you might want octal permissions of 775 instead.

Octal permissions are used in many places in Unix, hence in command tools like chmod, used to set and change permissions. They’re also used if you want to set your own umask.

Set the umask

Having mastered octal permissions, you now need to understand how a umask is applied to them. It would be far too simple for you to simply specify the umask as the octal permissions, so, as the name suggests, the number you set as a umask is subtracted from the default octal permissions. Default permissions are almost invariably 666 for files, and 777 for folders, the latter to allow for search. Thus the default user umask is 022:

• for a file, default permissions are then 666 – 022 = 644
• for a folder, default permissions are then 777 – 022 = 755, as we saw with the folder above.

To return to my example of someone who is sharing folders with colleagues in their group, and all of them need both read and write access to those shared folders and files, a simple way to accomplish this is for each to change their user umask to 002 from the default of 022. To do that as an admin user, enter the command
sudo launchctl config user umask 002
But before you use that, check there’s a folder at /private/var/db/com.apple.xpc.launchd/config. If there isn’t, that command will result in an error that you can correct by creating that folder.

This applies to all files and folders created by the processes run by a user, no matter where they are created, so extends beyond their shared folders.

Setting a system umask should be exceedingly rare, as that alters the permissions of folders and files created by macOS background services and whole lot more, and could cause utter chaos or security problems. If you really need to, use the same command but with system instead of user in the command line.

Whenever you have changed either the user or system umask, you need to restart your Mac to ensure the new setting is enforced.

Exceptions

Setting a umask doesn’t guarantee that every new folder and file will be created with those permissions, though, as processes with root privileges can set their own umask and are also able to set custom permissions where they wish. If you find a third-party app not respecting the user umask, when there’s no good reason to do different, contact its developer and complain. Good behaviour is essential for apps that work in shared environments.

References

Apple’s detailed support note
man chmod

By 1883, Walter Crane was a successful illustrator who had also established himself as a painter of repute. He was associated with members of the Pre-Raphaelite Movement, including William Morris, although Crane’s paintings remained distinctive and usually strongly narrative.

Like Morris, Crane was a socialist and from 1883 joined a string of related organisations including the Fabian Society, the Social Democratic Federation, and the Socialist League. He also promoted and supported the arts and crafts movement, and played active roles in both the Art Workers Guild and the Arts and Crafts Exhibition Society. For each of these he provided support in the form of illustrations.

Following his earlier Renaissance of Venus (1877), in 1883 he took a contrasting view of La Primavera (Spring), featuring Flora bent picking daffodil flowers on a plain.

Crane’s allegorical narrative of life as a bridge appears unique to him. It shows a newborn baby arriving in the hand of a winged angel in a white punt/gondola, left of centre. The baby is handed over to a mother or nurse, fed at the breast at the bottom left corner, walking up the steps, and learning at the top. Children play, then grow into young adults, and marry as they reach the top of the bridge. Throughout this runs the thread of life.

The mature adult in the middle of the bridge (by its keystone) then ages steadily, bearing the whole globe during the descent. He then gains a long white beard and walking stick during the descent into old age, finally dying, his body being placed in the black punt/gondola, where it is attended by the angel of death. Grieving relatives stand on the shore and make their farewells, one cutting the thread securing the boat to the shore with a pair of traditional scissors.

Crane explained the theme of his Bridge of Life (1884) as “fortune and fame pursued and ever eluding the grasp; til the crown perhaps is gained, but the burden of the intolerable work has to be borne.” It was first shown at the Grosvenor Gallery, then toured venues in the East End of London during a period of social and labour unrest there.

The following year, he painted Pandora in an unusual interpretation that is only loosely connected with the myth of her releasing all the evils of man from a large urn. She is shown draped in grief over a substantial casket, and on its side panel are the figures of the three Fates. At the corners of the casket are guardian winged sphinxes, each clasping a sphere.

Crane’s illustration for Baby’s Own Aesop (1887), engraved by Edmund Evans, underlines many of the differences between his illustrations and narrative paintings. First, the illustration here supports the text on the page, and doesn’t stand alone from it. Look at the picture and you could hardly deduce the accompanying text, but put the two together and you can see how the picture depicts the narrative in the text. Illustrators also have to be careful to ensure that there are no disparities between their work and the text, although narrative paintings often depart from a literal representation.

There are other stylistic clues, such as the use of drawn outlines throughout illustrations, and plain, simple drawings, which are much more likely in illustrations than in standalone paintings, although from the late nineteenth century onwards these appeared increasingly in paintings.

In 1891, Crane visited the US to promote an exhibition of his work there. Unfortunately, he appeared at a meeting of anarchists in Boston and openly expressed his opinion that those found guilty of the Haymarket affair, a bombing at a demonstration in Chicago in 1886, had been wrongfully executed. Despite writing a letter of apology to the press, Crane’s engagements were cancelled and the visit proved disastrous.

From 1887, Crane’s paintings moved away from his socialist politics towards what he described as “the forces of nature in elemental play”. Among the finest of these is Neptune’s Horses.

He painted this oil study for Neptune’s Horses in about 1892. Although it draws its theme from classical mythology, its treatment centres on explaining how that might have originated. It also hints at a visual pun, as the English phrase commonly used to describe breaking waves is white horses.

His finished painting of Neptune’s Horses (1892) reverses that study and brings the god a little closer.

Crane’s book illustration of King Midas with his Daughter, published in 1893, is one of the few works telling this myth directly. It shows the hapless king surrounded by all the gold objects which he has touched, his daughter dead on his knee, cold and gold.

Crane appears to have painted occasional watercolour landscapes, including this view of a pair of tall Lombardy poplar trees on a Bit of the Avon in 1893. There are several rivers of that name in England, and the title may refer to a section known then as the Bit.

The Swan Maidens (1894) is an elaborate fantasy depiction of one of the most widespread folk tales, known in almost every culture recorded around the world. This centres on one or more supernatural females who transform from human to bird form, most generally a swan, or sometimes a goose. This is accomplished by their donning the skin of the bird, as shown here. Swan maidens are featured in William Morris’s epic poem The Earthly Paradise (1868-70), although Crane doesn’t appear to have illustrated an edition.

In the mid-1890s, Crane devoted much time to making woodcuts for an illustrated and decorative edition of Edmund Spenser’s epic The Faerie Queene.

His title page establishes the seriousness of this illustrated edition, completed in six volumes over the period 1895-97, and published in 1897 by George Allen.

Crane’s woodcuts are detailed and delicate, as shown in his opening image of The Patron of True Holinesse in Book 1, Canto 1. These reflect his longstanding involvement with William Morris and his Kelmscott Press, which published 53 books between its creation in 1891 and 1898.

References

Wikipedia

O’Neill M (2010) Walter Crane. The Arts and Crafts, Painting, and Politics, 1875-1890, Yale UP. ISBN 978 0 300 16768 9.

Over the last few weeks, as I’ve been digging deeper into Spotlight local search, what seemed at first to be fairly straightforward has become far more complex. This article draws together some lessons that I have learned.

Apple’s search patents have been abandoned

Having tracked down a batch of Apple’s patents relating to search technologies that are likely to have been used in Spotlight, I was surprised to see those have been abandoned. For example, US Patent 2011/0113052 A1, Query result iteration for multiple queries, filed by John Hörnkvist on 14 January 2011, was abandoned five years later. I therefore have no insights to offer based on Apple’s extant patents.

Search is determined by index structure

Spotlight indexes metadata separately from contents, and both types of index point to files, apparently through their paths and names, rather than their inodes. You can demonstrate this using test file H in SpotTest. Once Spotlight has indexed objects in images discovered by mediaanalysisd, moving that file to a different folder breaks that association immediately, and the same applies to file I whose text is recognised by Live Text.

Extracted text, that recovered using optical character recognition (Live Text), and object labels obtained using image classification (Visual Look Up) are all treated as content rather than metadata. Thus you can search for content, but you can’t obtain a list of objects that have been indexed from images, any more than you can obtain Spotlight’s lexicon of words extracted as text.

Language

Spotlight’s indexes are multilingual, as demonstrated by one of Apple’s earliest patents for search technology. Extracted text can thus contain words in several languages, but isn’t translated. Object labels are likely to be in the primary language set at the time, for example using the German word weide instead of the English cattle, if German was set when mediaanalysisd extracted object types from that image. You can verify this in SpotTest using test file H and custom search terms.

If you change your Mac’s primary language frequently, this could make it very hard to search for objects recognised in images.

Search method makes a difference

The Finder’s Find feature can be effective, but has a limited syntax lacking OR and NOT unless you resort to using Raw Query predicates (available from the first popup menu).* This means it can’t be used to construct a search for text containing the word cattle OR cow. This has a beneficial side-effect, in that each term used should reduce the number of hits, but it’s a significant constraint.

The Finder does support some search types not available in other methods such as mdfind. Of the image-related types, John reports that kMDItemPhotosSceneClassificationLabels can be used in the Finder’s Find and will return files with matching objects that have been identified, but that doesn’t work in mdfind, either in Terminal or when called by an app. Other promising candidates that have proved unsuccessful include:

• kMDItemPhotosSceneClassificationIdentifiers
• kMDItemPhotosSceneClassificationMediaTypes
• kMDItemPhotosSceneClassificationSynonyms
• kMDItemPhotosSceneClassificationTypes.

One huge advantage of mdfind is that it can perform a general search for content using wildcards, in the form
(** == '[searchTerm]*'cdw)

Using NSMetadataQuery from compiled code is probably not worth the effort. Not only does it use predicates of different form from mdfind, but it’s unable to make use of wildcards in the same way that mdfind can, a lesson again demonstrated in SpotTest. mdfind can also be significantly quicker.

For example, you might use the form
mdfind "(kMDItemKeywords == '[searchTerm]*'cdw)"
in Terminal, or from within a compiled app. The equivalent predicate for NSMetadataQuery would read
(kMDItemKeywords CONTAINS[cdw] \"cattle\")

Another caution when using NSMetadataQuery is that apps appear to have their own single NSMetadataQuery instance on their main thread. That can lead to new queries leaking into the results from previous queries.

Key points

• Spotlight indexes metadata separately from contents.
• Text recovered from images, and objects recognised in images, appear to be indexed as contents. As a result you can’t obtain a lexicon of object types.
• Indexed data appear to be associated with the file’s path, and will be lost if a file is moved within the same volume.
• Text contents aren’t translated for indexing, so need to be searched for in their original language.
• Object types obtained from images appear to be indexed using terms from the primary language at the time they are indexed. If the primary language is changed, that will make it harder to search for images by contents.
• The Finder’s Find is constrained in its logic, and doesn’t support OR or NOT, although using Raw Queries can work around that.
• mdfind is most powerful, including wildcard search for content.
• NSMetadataQuery called from code uses a different predicate format and has limitations.

I’m very grateful to Jürgen for drawing my attention to the effects of language, and to John for reporting his discovery of kMDItemPhotosSceneClassificationLabels.

• I’m grateful to Jozef (see his comment below) for reminding me that there is a way to construct OR and NOT operations in the Finder’s Find, although it’s not obvious, and even when you know about it you may well find it difficult to use. I will explain more about this in another article next week.

Apple has just released its weekly update to XProtect for all supported versions of macOS, bringing it to version 5313. As usual, Apple doesn’t release information about what security issues this update might add or change.

This version adds 4 new rules for components of MACOS.MISOMESA and 7 for MACOS.MISOMAGIC, both new codenames in the Yara file, it also adds a new rule for MACOS.SOMA.AUENC, another Soma/Amos component, and amends the existing detection rule for MACOS.DUBROBBER.CHBI.

You can check whether this update has been installed by opening System Information via About This Mac, and selecting the Installations item under Software.

A full listing of security data file versions is given by SilentKnight and SystHist for El Capitan to Tahoe available from their product page. If your Mac hasn’t yet installed this update, you can force it using SilentKnight or at the command line.

If you want to install this as a named update in SilentKnight, its label is XProtectPlistConfigData_10_15-5313

Sequoia and Tahoe systems only

This update has now been released for Sequoia and Tahoe via iCloud. If you want to check it manually, use the Terminal command
sudo xprotect check
then enter your admin password. If that returns version 5313 but your Mac still reports an older version is installed, you may be able to force the update using
sudo xprotect update

Not everyone in the Dutch Republic enjoyed a Golden Age of material wealth. There were some who found worldly goods and pleasures of the flesh were hollow and fleeting, and expressed that in a new sub-genre of Vanitas.

This stems from a long Christian tradition of the worthlessness of earthly possessions, and the promise of life after death. These are crystallised in the wisdom literature of the Bible, in particular a verse from Ecclesiastes, given in the Latin translation of the Vulgate as vanitas vanitatum omnia vanitas, or vanity of vanities, all is vanity, although here the word vanity refers to feelings of emptiness and futility, rather than conceit.

Vanitas paintings thus point to:

• the brevity of life on earth,
• the imminence of death,
• the worthlessness of earthly riches,
• the futility of earthly pursuits and pleasures.

Because those are abstract concepts, the challenge in every Vanitas painting is to find the right symbols, generally accomplished through an allegorical language. They also overlap with other themes in painting such as the Memento mori, the reminder of one’s own mortality.

These have their origins in the Flemish Renaissance, as in Jan Sanders van Hemessen’s Vanitas from about 1535-40. This features an unusual androgynous angel with butterfly wings, cradling a human skull with fragmentary Latin inscriptions. Within the skull is an inset window, through which there is a tiny landscape view. This artist started his career in Antwerp, and is thought to have moved to Haarlem after 1550.

When Vanitas paintings first became popular in the Dutch Republic, they were most commonly expressed in carefully composed still lifes. Clara Peeters’ Fruit, Dead Birds and a Monkey (1615-20) shows a typically strange collection of objects: at first glance a basket of fruit, but the grapes are covered with bloom, a peach is going rotten, and there is a fly on an apple. The little monkey, busy feeding from nuts, is gazing at a small pile of dead birds.

These became elaborate and contrived at times, and sometimes involved a self-portrait.

In Peeters’ Vanitas Portrait of a Woman, the artist gazes into the distance, probably a carefully-angled mirror to see her own reflection. Beside her head is a bubble, a sign of Vanitas. In front of her, on the table, are the contents of a still life, with the worldly symbols of Vanitas: gold and silver coins, jewellery, a couple of dice, with their association with chance and earthly pleasures such as gambling.

In Cornelis de Vos’s Allegory on Transitoriness (1620-29), a mother, possibly the artist’s wife, sits looking full of Vanitas, as her two children blow soap bubbles. Around her, the family’s most valuable possessions are piled up: gold, silver, porcelain, a lute, a string of pearls and other jewellery, and the younger child’s foot rests on a sack of cash. De Vos was Flemish, with his workshop in Antwerp, and often collaborated with Peter Paul Rubens.

Carstian Luyckx, another Flemish painter from Antwerp, brings in additional objects to his undated Allegory of Charles I of England and Henrietta of France in a Vanitas Still Life. These include a globe representing the physical world, the gall from a tree, a snuffed-out candle, seashells, and coral. He uses another common device found in Vanitas painting: an open book, here showing King Charles I, who was executed in 1649, and his wife Henrietta Maria of France, who was deposed as queen of England by the civil wars, forcing her to flee to France in 1644.

David Bailly’s Self-Portrait with Vanitas Symbols (1651) is a complex web of allegory containing multiple portraits referring to the past. The figure shows him as a much younger man, holding the maulstick he used in painting. His true self-portrait at the time is in the painting held with his left hand. Next to that is a painting of his wife, who had already died, and a ghostly image of her is projected onto the wall behind the wine glass.

Gathered in front of the artist are ephemera and other Vanitas objects: the snuffed-out candle, a glass of wine, flowers, and soap bubbles, together with a string of pearls and a skull. If that message isn’t clear enough, he provides the quotation on a piece of paper: vanitas vanitum et omnia vanitas, together with his signature and date. This painting is also unusual for its innovative use of colour and monochrome passages to distinguish its features from their ground. Bailly worked in the city of the Dutch Republic that became most strongly associated with Vanitas painting, Leiden.

Gerard ter Borch’s younger half-sister Gesina modelled for some of his paintings and trained as a painter herself. Between 1667-69, brother and sister painted this Memorial Portrait of Moses ter Borch (1645-1667) to commemorate their younger brother Moses, also a promising artist, who was killed in the Second Anglo-Dutch War in the summer of 1667. Centred on his full-length posthumous portrait, he’s surrounded by Vanitas symbols, including a snake, butterfly, watch, a small pipe, armour, an hourglass, a skull, shells, weapons, snails, fungal decay, and withering flowers. The ter Borchs worked from Amsterdam, although Gerard seems to have travelled more widely.

Evert Collier’s A Vanitas from 1669 is another collection, showing additional objects which became involved in the allegory, including a sword, armour, fine fabrics, and ornamental feathers. Collier was born in North Brabant, trained in Haarlem, then moved to Leiden.

Some later Vanitas paintings developed the theme of young boys blowing bubbles, as in Karel Dujardin’s Boy Blowing Soap Bubbles, an Allegory on the Transitoriness and Brevity of Life from 1663. Dujardin worked in Amsterdam.

There are many more powerful PDF and image editors, yet plenty of us use Preview for those basic little tasks, where we don’t need the complications of a heavyweight. Preview isn’t without its faults, though. It can mutilate PDF annotations made by other apps, and sometimes unexpected things happen. To deal with those it has one feature that’s almost unique among PDF and image editors: it automatically saves versions using the macOS versioning system. This article explains how to make use of that.

Ask to save changes when closing documents

One important control over the behaviour of Preview and many other apps that you may not be aware of is this in the Windows section of Desktop & Dock settings. When combined with apps that use the macOS versioning system its effects are significant.

Ignoring versioning for the moment, when this setting is turned on, if you go to close an open document that has unsaved changes, before it’s closed you’ll be asked whether you want to save that changed document. This is a long-standing safety net that continues to protect us from losing lots of work by accident.

When this setting is turned off, apps may still ask you whether you want to save unsaved changes before closing a document unless the app uses the macOS versioning system. In that case, the app automatically saves a new version without offering any option. This might appear inappropriate, but as that’s non-destructive, it avoids interrupting your workflow: you can always revert to the previous version of that document, provided that you’re aware that it has been saved automatically.

If you’re not aware of what’s going on here, and how the versioning system works, this can cause odd effects you can demonstrate using Preview.

Preview’s saving grace

To see how Preview handles versions and the effect of that setting, find a copy of a suitable PDF or image file and duplicate it in the Finder. Name one copy something like testSavesOff, and the other testSavesOn. Set Ask to save changes when closing documents off to begin with, and open testSavesOff in Preview.

Now perform some destructive editing on that document without saving it, here a radical crop.

Leave it a couple of minutes before closing the document. Following that setting, Preview shouldn’t ask you whether to save the changed document, but will simply close it. Then quit Preview.

Now set Ask to save changes when closing documents on, and repeat the same sequence with testSavesOn instead. When you try to close that document, Preview should now ask you whether you want to save the changed document, to which you should click on Revert Changes to set the document back to its previous state instead.

Inspect the two documents using Quick Look and you’ll see that testSavesOn hasn’t changed, but testSavesOff has, although in neither case did you save those changes yourself.

All in the versions

Although you can see what has happened using Preview’s Revert To menu command, the clearest way to see what has happened to those two documents is to open them using my free Revisionist, which shows their saved versions.

testSavesOn has three saved versions. The current one is the same as the original, but the second version shows the destructive edit that you didn’t save.

testSavesOff has two saved versions, the original, and the current version is that after the destructive edit, which you also didn’t save.

Thanks to Preview’s use of the macOS versioning system, either way you’ve still got access to both versions of that document.

One point to note, though, is that the versioning system doesn’t automatically clean up old versions for you. When you’ve finished editing a document in Preview and don’t want to retain its old versions, delete them either using Revert To in Preview, or with Revisionist. Versions are only retained for the original document as long as it’s stored on the same volume. So you can also wipe old versions by duplicating a document and trashing the original, or copying it to another volume. Once they’re gone, you can’t restore them, as not even Time Machine can back up versions.

The closest an artist comes to painting with pure pigment is when applying soft pastel to the ground. From the earliest cave art, humans have applied powdered earths and chalks to surfaces. Some of the oldest surviving masterpieces made using coloured chalks include those of Leonardo da Vinci, and are sometimes incorrectly referred to as pastels.

An example is this drawing of Isabella d’Este from 1500, described here as using “black and red chalk, yellow pastel chalk on paper”. But there is no such thing as “pastel chalk”, any more than there is “oil watercolour”.

Pastels are much more than just a stick of pigmented chalk or coloured earth, as they’re made by mixing pigment and a bulking powder, with water containing a gum or glue, into a thick dough-like paste. That paste is dried slowly in sticks to become sufficiently firm as to be capable of being sharpened and applied to paper or another ground.

Painting in pastels requires many sticks of different colours; although those can be blended on the paper or ground, pastels don’t mix like oil paints to produce good intermediate colours. You can’t paint properly in pastels with just half a dozen different colours, but need dozens or hundreds to support a broad spectrum. This shows one of my sets of pastels, a Winsor & Newton boxed set of 200.

Careful assessment by Thea Burns has established that the earliest painter in pastels was probably Robert Nanteuil.

Nanteuil’s Portrait of Monseigneur Louis Doni d’Attichy, Bishop of Riez from 1663 is one of the first true pastel paintings, relatively small, but expertly worked. When these became popular in the eighteenth century they quickly became all the rage. Unlike oil paints applied in layers over a period of weeks, pastels adhere to the ground mechanically, and have no drying time. A good pastellist could produce a fine portrait in just a few sittings, making them far less demanding on both parties, much quicker, and of course considerably cheaper. The ‘look’ of pastel paintings also came into vogue, with flesh looking lifelike with a soft, matte finish.

Initially there were no fixatives to help the adhesion of pastel to ground, so they all had to be glazed, and even then didn’t prove as durable as a well-made oil painting. But at that price, only the very rich would care.

Next, mainstream artists started using pastels in preparatory work and sketches, here Charles Antoine Coypel’s dramatic portrait of Medea (c 1715).

One of the most brilliant of this first big wave of pastellists was Rosalba Carriera, whose work demonstrated that a good pastel painter could match the accomplishments of the best oil painters of the day. She had a painterly style at times, as shown in her rich marks in Africa, for which I don’t have a date.

In the fingers of a skilled pastellist, materials like hair and fur that had long challenged painters in oils became great strengths. Carriera’s superb Self-Portrait as ‘Winter’ from 1730-31 is a fine example, as seen in the detail below.

Look carefully and you can see individual grains of pastel that form each mark she made. She didn’t just apply her pastels dry and from the stick, but in places turned them back into a paste using water, and applied that to the paper with a brush.

The star pastellist of the middle of that century was undoubtedly Maurice Quentin de La Tour, whose works are readily seen in the Louvre and elsewhere.

De La Tour not only excelled at modelling softer surfaces and materials to which pastels are so suited, but tackled harder and glittery materials used in jewellery and the like. They’re particularly well shown in his Portrait of Marie-Josèphe of Saxony, Dauphine of France (1731–1767) (1756-60).

After de La Tour, the next brilliant pastellist was quite a contrast: Jean-Etienne Liotard, whose meticulous realism is just breathtaking. Applying his pastels to parchment rather than paper, he was able to paint painstakingly detailed works like The Chocolate Girl (c 1744-45). This shows how the medium was moving on from regular portraits.

Only when you see the patterned grain of the pastel on parchment does it become clear that this is not oil paint. I still marvel at the glass of water: surely a demonstration tour de force to make the viewer gasp in wonder.

Louise Élisabeth Vigée Le Brun’s simple portrait of a baby from about 1790 takes up from where Carriera and de La Tour had made their marks. This infant’s face is softly rendered, but their clothes are sketched in a loose style far in advance of oil paintings of the day.

Pastel painting remained popular through the nineteenth century, but its next major advances came with those around the Impressionists, rather than the core Impressionists, who overwhelmingly preferred oils.

Édouard Manet’s Woman Fastening Her Garter (1878-79) shows a motif many would associate more with Degas, and a spontaneous and sketchy style, with an emphasis on form.

Paul César Helleu was radical and exciting in his pastels; his portrait of Consuelo Vanderbilt, Duchess of Marlborough (c 1900) combines perfect, smooth blending over her face with vigorous mark-making through the fabrics and the ornate frame of the chair, as shown in the detail below.

Edgar Degas was another innovative painter in pastels, whose work encouraged Odilon Redon to take the medium on into the twentieth century.

His recurrent theme of a small sailing boat, which kept appearing in Redon’s later paintings, was expressed most extensively in his pastels. Some, like Flower Clouds (c 1903), above, show the boat sketched in roughly, his paper being dominated by nebulous patches of colour from behind.

His best-known painting of the boat, The Yellow Sail (c 1905), below, was painted in pastel too. He exploits new and more intense pigments here, for the sparkling gems in the boat, and the clothing of the two women.

Although the period since has seen new media such as acrylics, there is still nothing else like painting in pure pigment.

Reference

Thea Burns (2007) The Invention of Pastel Painting, Archetype. ISBN 978 1 904982 12 3.

Look in the log, and Visual Look Up (VLU) on an Apple silicon Mac apparently involves a great deal of work, in both CPU cores and the neural engine (ANE). This article reports a first attempt to estimate power and energy use for a single VLU on an image.

To estimate this, I measured CPU, GPU and ANE power in sampling periods of 100 ms using powermetrics, and correlated events seen there with those recorded in a log extract over the same period, obtained using LogUI. The test was performed on a Mac mini M4 Pro running macOS 15.6.1, using Preview to perform the VLU on a single image showing a small group of cattle in an upland field. Power measurements were collected from a moment immediately before opening the image, and ceased several seconds after VLU was complete.

When used like this, powermetrics imposes remarkably little overhead on the CPU cores, but its sampling periods are neither exact nor identical. This makes it difficult to correlate log entries and their precise timestamps with sampling periods. While powermetrics gives power use in mW, those measurements aren’t calibrated and making assumptions about their accuracy is hazardous. Nevertheless, they remain the best estimates available.

Log narrative

The first step in log analysis was to identify the starting time of powermetrics sampling periods. Although execution of that command left no trace in its entries, as it has to be run with elevated privileges using sudo, its approval was obvious in entries concluding
30.677182 com.apple.opendirectoryd ODRecordVerifyPassword completed
A subsequent entry at 30.688828 seconds was thus chosen as the start time for sampling periods, and all times given below as given in seconds after that time zero.

The following relevant events were identified in the log extract at elapsed times given in seconds:

• 1.3 com.apple.VisionKit Signpost Begin: “VisionKit MAD Parse Request”
• 1.3 com.apple.mediaanalysis Running task VCPMADServiceImageProcessingTask
• 1.4 ANE started and an ObjectDetectionModel run for 0.2 s
• 1.6 ANE activity and a NatureWorldModel run for 0.25 s
• 2.0 ANE activity for 0.15 s
• 2.4 ANE activity for 0.1 s
• 8.1 ANE activity and a UnifiedModel run for 0.01 s
• 8.1 PegasusKit queried Apple’s SMOOT service, the external connection used to populate the VLU window.

Thus, the ANE was run almost continuously from 1.4-2.2 seconds after the start of sampling, otherwise was used little over the total period of about 9 seconds. Over that period of activity, an initial model used to detect objects was succeeded by a later model to identify objects in a ‘nature world’.

Power and energy estimates

From the log record, it was deduced that the VLU was started in powermetrics sample 10 (1.0 seconds elapsed), and essentially complete by sample 75 (7.5 seconds elapsed), a period of approximately 6.5 seconds, following which power use was low until the end of the sampling periods. All subsequent calculations refer to that series of samples and period of time.

Sums, averages and maxima of power measurements for that period of 6.5 seconds are:

• CPU 64,289 mW total, 989 mW average, 7,083 mW maximum (10 P cores)
• GPU 3,151 mW total, 48 mW average, 960 mW maximum (20 cores)
• ANE 1,551 mW total, 24 mW average, 671 mW maximum
• total 68,991 mW total, 1,061 mW average, 7,083 mW maximum.

Thus for the whole VLU, 93% of power was used by the CPU, 4.6% by the GPU, and only 2.2% by the ANE.

For comparison, in the M4 Pro chip running maximal in-core loads, each P core can use 1.3 W running floating point code, and 3 W running NEON code. The chip’s 20-core GPU was previously measured as using a steady maximum power of 20 W, with peaks at 25 W.

As each power sample covers 0.1 seconds, energy used during each sampling period is power/0.1, thus the total energy used over the 6.5 second period of VLU is:

• CPU 6.4 J
• GPU 0.3 J
• ANE 0.2 J
• total 6.9 J.

Those are small compared to the test threads used previously, which cost 3-8 J for each P core used.

Power over time

Power used in each 100 ms sampling period varied considerably over the whole 10 seconds. The chart below shows total power for the CPU.

Highest power was recorded between samples 10-25, corresponding to 1.0-2.5 seconds elapsed since the start of measurements, and most events identified in the log. Later bursts of power use occurred at about 4.2 seconds, and between 6.6-7.1 seconds, which most probably corresponded to opening the info window and performing the selected look-up.

Almost all power use by the neural engine occurred between 1.5-2.1 seconds, correlating well with the period in which substantial models were being run.

Peak GPU power use occurred around 1.0-1.5 seconds when the image was first displayed, at 3.1-3.2 seconds, and between 6.5-7.4 seconds. It’s not known whether any of those were the result of image processing for VLU as GPU-related log entries are unusual.

Composite total power use demonstrates how small and infrequent ANE and GPU use was in comparison to that of the CPU.

Conclusions

Given the limitations of this single set of measurements, I suggest that, on Apple silicon Macs

• power and energy cost of VLU is remarkably low;
• the great majority of work done in VLU is performed in the CPU;
• although use of the neural engine may result in substantial performance improvements, VLU doesn’t make heavy demands on the neural engine in terms of power or energy use;
• VLU may appear impressive, but it’s not actually that demanding on the capability of the hardware.

Passing on from the circle of gluttons, Virgil leads Dante past the great foe of Plutus, a wolf-like creature who is chided by Virgil, and so they descend to the next circle, densely populated by avaricious misers and prodigal spendthrifts.

Plutus most probably refers here to a composite of the god of wealth, thus the root of the evil in these souls in this fourth circle of Hell, and Pluto, one of the gods of the classical underworld. Either of those roles justifies Dante’s description of him as the great enemy of mankind.

As opposites, the two groups of spirits are locked against one another, each rolling great boulders around in opposition. When their rocks crash together, they turn about and push in the other direction, and so on for eternity. Among those whose sin is avarice are many clerics, including cardinals and popes.

Virgil explains the role of Fortune in all this, that neither group of sinners can ever be satisfied with the riches that she has. Thus both the avaricious and the spendthrifts curse the angelic Fortune for their own sins.

Dante is led by Virgil past a dark spring to the swamp of the River Styx, so entering the fifth circle of Hell, where other souls covered in mud are attacking one another, punching and kicking as hard as they can. These are the sinners who were overcome with anger. Also in the swamp are their opposites, the mournful and miserable, whose breath bubbles up through the muddy waters.

The two reach the foot of a high tower, on top of which two flames are lit to signal to another tower in the far distance. This brings them a ferry, this time rowed by a man who Virgil calls Phlegyas, who is to carry the pair across the Stygian waters in his boat.

Phlegyas is a character drawn from classical legend and myth, including Virgil’s Aeneid. After Apollo raped his daughter Coronis, Phlegyas flew into a fit of rage and burned the temple of Apollo at Delphi, so the god killed him and sent him to the underworld to undergo eternal torment.

As Phlegyas rows Dante and Virgil across rough water, the spirit of Filippo Argenti, an arrogant Florentine who is hated by Dante, rises out of the water and tries to capsize their boat.

Dante tells him to be off, and Virgil assists in pushing him back into the river. They see Argenti’s ghost cast among those fighting on the shore, where he is torn apart by them, to Dante’s delight.

Their boat then approaches the moated city of Dis, in the depths of Hell (circles six to nine), where Phlegyas lands them. Virgil goes forward to secure their admission, but the gate to the city is slammed shut on him.

The artists

William Blake (1757–1827) was a British visionary painter and illustrator whose last and incomplete work was an illustrated edition of the Divine Comedy for the painter John Linnell. Most of his works shown in this series were created for that, although he did draw and paint scenes during his earlier career. I have a major series on his work here.

Gustave Doré (1832–1883) was the leading French illustrator of the nineteenth century, whose paintings are still relatively unknown. Early in his career, he produced a complete set of seventy illustrations for translations of the Inferno, which were first published in 1857 and continue to be used. These were followed in 1867 by more illustrations for Purgatorio and Paradiso. This article looks at his paintings.

References

Wikipedia
Danteworlds

Robin Kirkpatrick (trans) (2012) Dante, The Divine Comedy, Inferno, Purgatorio, Paradiso, Penguin Classics. ISBN 978 0 141 19749 4.
Richard Lansing (ed) (2000) The Dante Encyclopedia, Routledge. ISBN 978 0 415 87611 7.
Guy P Raffa (2009) The Complete Danteworlds, A Reader’s Guide to the Divine Comedy, Chicago UP. ISBN 978 0 2267 0270 4.
Prue Shaw (2014) Reading Dante, From Here to Eternity, Liveright. ISBN 978 1 63149 006 4.

I hope that you enjoyed Saturday’s Mac Riddles, episode 323. Here are my solutions to them.

1: Well-guarded like West Berlin was, it holds your greatest secrets.

Click for a solution

secure enclave

Well-guarded (secure) like West Berlin was (an enclave surrounded by East Germany), it holds your greatest secrets (what it does).

2: Motor nerve processes your images.

Click for a solution

neural engine

Motor (engine) nerve (neural) processes your images (what it does).

3: Cloth or worsted to connect it all together.

Click for a solution

fabric

Cloth or worsted (both are fabrics) to connect it all together (what it does).

The common factor

Click for a solution

They are relatively new features in Apple silicon chips.

I look forward to your putting alternative cases.

At first sight, this might seem a simple question to answer. Allow me to demonstrate that it’s more complex, has changed over time, and still hasn’t been resolved.

Before 1984

Although there were exceptions, before the Mac most file systems that we were likely to encounter were simple. Each file consisted of stored data, together with a small entry in the file system’s metadata containing information such as the file’s name and its time and date of creation. By convention, as that’s not stored with the file’s data, that isn’t included in its size.

The only complication here was that storage is divided up into blocks, so in addition to the file’s actual size, we’d also want to know the total size taken by the storage blocks it used, as any given block couldn’t be shared between files, a figure often known as size on disk, and dependent on the size of those blocks. If the block size is 4,096 bytes, then any file whose data was equal to or smaller than that had a size on disk of 4,096 bytes, 4 KiB or 4.096 KB. (There are 1,000 bytes in a KB, but 1,024 bytes in a KiB.)

Classic Mac OS

One of the many innovations in the first Mac was its file system MFS, in which every file has two forks, one the traditional data fork, the other a resource fork for storing structured blobs of data termed resources. As MFS was replaced by HFS and eventually HFS+, those resource forks continued.

Resource forks often reached considerable sizes, and although they are stored separately from data forks in HFS+, Apple usually gave the sizes of the two forks, as shown in this dialog, where the size of the resource fork is 117,836 bytes, almost as large as the file’s 144,788 bytes of data. Information about the size of that file’s entry in the file system data, its attributes, wasn’t given, though.

HFS+ in Mac OS X

In the early years of Mac OS X, there was controversy as to whether it should continue supporting the use of resource forks, and most of their uses were replaced by flattened data files arranged in bundles. Nevertheless, in Mac OS X 10.4, HFS+ became multi-forked with what were dubbed extended attributes or xattrs, one type being com.apple.ResourceFork, the classic resource fork. However, the practice of giving separate sizes for the data fork and other forks died.

APFS

When APFS was released in 2017, it changed the way in which xattrs are stored, as explained here. Now, each file can consist of:

1. file system attributes, stored in the file system metadata structures;
2. small xattrs of up to 3,804 bytes, stored separately from its attributes, but in file system metadata;
3. large xattrs over 3,804 bytes, typically including any com.apple.ResourceFork, stored as data streams with separate records;
4. data, stored in storage blocks as set out in their file extents.

As demonstrated using crafted files, initially the Finder ignored items 1-3 in stating file size, and just gave that of 4, the data, although it could instead still have been including resource forks, of course.

The size of this text file is given as 391 bytes in the Finder’s Get Info in High Sierra, but as you’ll see below it contains over 90,000 bytes of extended attributes that figure simply ignores.

macOS Sequoia

Here are the sizes given for another of my specially crafted demonstration files, for APFS in macOS 15.6.1 Sequoia.

According to the Finder’s Get Info dialog, this file contains 263,195 bytes and occupies 266 KB on disk. On an SSD with the standard 4 KiB block size, that should be 65 blocks, or 266,240 bytes, as given correctly. There’s something amiss with that file, though, as it claims to be a Zip archive but has an image thumbnail.

Listing its xattrs using xattred reveals no less than 14, including two of 80 KB each. xattred claims it has a data fork size of 183,136 bytes and 161,406 bytes in xattrs, making a total size of 344,542 bytes, which is nowhere near that given by the Finder. (It’s the com.apple.ResourceFork xattr, a classic resource fork, that contains the image thumbnail displayed by QuickLook instead of the normal Zip file icon.)

To discover how the Finder arrives at a size of 263,195 bytes, we need to subtract the data size from that, making 80,059 bytes, the size of the file’s resource fork or com.apple.ResourceFork xattr. So, without being explicit about forks, it’s behaving the same as in Classic Mac OS. You might find that puzzling, given that there’s another xattr of the same size that it’s ignoring, and a dozen more that don’t get a look-in. As the use of com.apple.ResourceFork xattrs has long been discouraged if not deprecated, isn’t that a strange behaviour? The more so when modern xattrs that Apple has introduced relatively recently, such as com.apple.quarantine, com.apple.macl and com.apple.provenance, are ignored.

The deeper you look into this, the more puzzling it becomes. Here are the same file’s figures as shown in Precize.

Sizes are given a few lines down, from two sources, URL Keys and the file system (FileManager), and they also differ. There’s a list of xattrs given at the foot of this window, but that only gives 12 and ignores com.apple.ResourceFork and com.apple.FinderInfo.

In the macOS API, code can obtain values for file sizes from its URL. Two keys are available, fileSizeKey and totalFileSizeKey. The first gives the data size, and the second is the same ‘total’ as that shown by the Finder, i.e. data + com.apple.ResourceFork xattr, but excluding all other xattrs. Apple’s documentation explains those as:

• fileSize is “the total file size, in bytes”
• totalFileSize is “the total displayable size of the file, in bytes. The allocated size in bytes may include space used by metadata.”

FileManager also gives the data size in its FileAttributeKey.size, but doesn’t give any for xattrs, even com.apple.ResourceFork. The size of the Metadata shown for the File system is instead calculated by totalling the individual sizes of all its xattrs, including com.apple.ResourceFork and com.apple.FinderInfo.

This may appear to be nit-picking, but data sizes are given to the exact number of bytes, and the size on disk for non-sparse files should always be within 4,095 bytes of the data size. Yet accounting for xattrs remains rooted in Classic Mac OS from 25 years ago and still pretends that xattrs either don’t exist, or don’t take any space.

In the first article of this pair looking at paintings of windmills, I covered traditional views up to the first of the pre-Impressionists. This article takes this account from around 1850 up to the period between the two World Wars. Although the development of steam power during the nineteenth century brought great changes to many industries, windmills continued to flourish until the middle of the century, and even then they only declined gradually until the Second World War.

Samuel Palmer’s Summer Storm near Pulborough, Sussex from about 1851 refers to Dutch landscape painting, in a very Kentish context. A storm is seen approaching the rolling countryside near Pulborough, now in West Sussex. On the left, in the middle distance, a small bridge leads across to a hamlet set around a prominent windmill, whose blades are blurred as they are being driven by the rising wind.

Windmill styles differ outside northern Europe. When Jean-Léon Gérôme travelled down the River Danube in about 1855, he claimed to have witnessed this moving scene of Recreation in a Russian Camp, Remembering Moldavia (1855). A group of Russian soldiers in low spirits is being uplifted by making music, under the direction of their superior. Gérôme has captured an atmosphere which few of his other paintings achieved: the marvellous light of the sky, the skein of geese on the wing, and the parade of windmills in the distance, all draw together with the soldiers in their sombre greatcoats.

The following year, JC Dahl’s Burning Windmill at Stege is an unusual fire-painting following a traditional sub-genre of the Dutch Golden Age. Although painted well before Impressionism, Dahl echoes the red of the flames in the field and trees to the left of the windmill, and even in his signature.

During the winter of 1864, Johan Jongkind returned to the Netherlands, where he painted this Winter View with Skaters, which is more overtly pre-Impressionist.

Jongkind’s watercolour sketch of a Windmill at Antwerp of 1866 is even more painterly.

Claude Monet’s second visit to the Netherlands in 1874 ensured that The Windmill on the Onbekende Gracht, Amsterdam (1874) became a part of the history of Impressionism. This shows a windmill known as Het Land van Beloften, De Eendracht or De Binnen Tuchthuismolen, which was built in the late seventeenth century, and was moved from there to Utrecht just a couple of years after Monet painted it on the banks of the River Amstel.

Frits Thaulow’s painstakingly detailed View of Amerikavej in Copenhagen (1881) shows a windmill in the background, where it’s being used to provide power to the adjacent industrial site.

Volodymyr Orlovsky’s Ukrainian Landscape from 1882 shows one of the distinctive windmills on the elevated bank alongside a major river and its more populated floodplain to the right.

It may not have been Monet who first made the visual association between Dutch windmills and fields of tulips in flower, but his 1886 painting of Tulip Field in Holland must be its best-known depiction.

When Vincent van Gogh moved to Paris in 1886, he stayed with his brother Theo in Montmartre. He painted a series of marvellous views of the remaining windmills there, including the most famous of them all, Le Moulin de la Galette (1887), in whose gardens Renoir had painted his Bal du moulin de la Galette a decade earlier.

Paul Signac’s Rotterdam. The Windmill. The Canal. Morning (1906) is a Divisionist view of a windmill in the centre of this major port.

It was a Dutch painter who took windmills from Impressionism to the modernist styles of the twentieth century: Piet Mondrian.

Piet Mondrian’s gentle nocturne of Oostzijdse Mill on the River Gein by Moonlight from about 1903 is one of several views of windmills that he painted in Impressionist and post-Impressionist style.

When he started experimenting with vibrant colour and patterned brushstrokes in about 1908, this painting of a Mill in Sunlight marks his point of departure.

The Red Mill (1911) continues Mondrian’s move towards areas of flat colour. That year he left the windmills of Amsterdam and moved to Paris. To mark his move into the avant garde of that city, he dropped the second ‘a’ from his surname, going from Mondriaan to Mondrian. He became increasingly influenced by Georges Bracque and the Cubist works of Pablo Picasso, and the purely abstract paintings for which he remains well-known today.

Serhii Svitoslavskyi’s Ukrainian Landscape with Windmills, probably from about 1911, shows a small cluster of windmills with grazing livestock.

By the end of the First World War, milling grain had become more centralised, and the hundreds of thousands of small windmills across northern Europe lost their business. A few have been preserved, and some are still used for specialist products such as stoneground flour. But the unmistakable sight of a windmill on the skyline had been lost from much of the land.

During the 1930s, the Raviliouses started spending time in Sussex, where they became close friends with Peggy Angus, whose house The Furlongs at Beddingham, East Sussex, became a second home. Eric Ravilious became particularly fond of painting the chalk downs there, as in his Windmill (1934). This isn’t a windmill in the traditional sense, but a smaller wind-driven pump to extract water from the chalk, mainly for irrigation.

Unlike Apple’s bundled apps in macOS, the great majority of third-party software needs to run on more than just the latest version of macOS. This is a challenge when there’s a major redesign of the interface, as there is in macOS Tahoe. While OS 26 may bring greater consistency across platforms, it’s also important to developers and users that it doesn’t sacrifice consistency between, say, Sequoia and Tahoe.

As I showed recently in my simple little utility DropSum, at times the appearance of windows can be very different between macOS 15 Sequoia and 26 Tahoe. DropSum uses AppKit rather than SwiftUI, and is a little unusual in applying colour to its window. This is used in a popular mechanism to indicate when that window is ready to receive a file being held over it, by changing the view colour from systemOrange to systemGreen. As that coloured view extends over the controls in the window, I have had to be careful to ensure those controls remain readable in both appearance modes, with the Reduce transparency and Increase contrast settings in Accessibility settings, and across recent versions of macOS. That hasn’t proved easy, so what you see below appears to be the best compromise I can achieve. DropSum doesn’t alter its settings or behaviour between different versions of macOS, instead relies on the host API’s appearance modes and Accessibility settings.

Although I have confirmed the observations below on individual systems, to make comparison easier here each screenshot shows two DropSum windows. The upper is running in a Tahoe beta 7 VM (where the window title is left-aligned), and the lower in Sequoia 15.6.1 on the host (where the window title is centred).

Light mode

In both light appearance modes, all boxed text is displayed in black on a white background, making their contents and controls clear. There are marked differences in the hues seen, though, with both systemOrange and systemIndigo (chosen for better contrast in labels) being more intense in Tahoe than Sequoia. As expected, Tahoe’s controls are slightly larger, and the corners of all four text boxes are rounded rather than square.

Reducing transparency made little difference in either rendering, merely whitening the window title bar.

Increasing contrast changes the intensity of some colours. In Sequoia, systemOrange is lightened, and in both windows the traffic light buttons at the top left, and the Clear button, are darkened. Otherwise the most obvious effect is the outlining of all components, including each of the controls.

Apps built to support macOS 26 thus appear consistent between macOS 15 and 26 when used in light mode.

Dark mode

Most apparent here are the contrasting effects of dark mode on the background of the four text boxes. In Sequoia, their background is the systemOrange of the coloured view, but in Tahoe it’s black. The latter makes the text contents more readable, while unselected text in Sequoia is more difficult to read.

Increasing contrast has different effects on colours when in dark mode. In Sequoia all colours including the systemOrange view become slightly lighter, whereas in Tahoe the contrast of some is enhanced, with black becoming blacker and white whiter, but there’s little discernible change in systemOrange, which remains significantly more intense than in Sequoia. systemIndigo is rendered lighter though, making it more difficult to read against the systemOrange background.

Reduce transparency

Apple describes this effect as replacing “the transparent effect used on some backgrounds in macOS with a solid background to improve contrast and readability.” In both Sequoia and Tahoe, and in both appearance modes, the only effect observed is a lightening of the window title bar, as the rest of the window is already opaque.

Increase contrast

Apple describes this as increasing “the contrast of items on the screen (such as borders around buttons or boxes) without changing the contrast of the screen itself.” Although the borders are the most prominent effect in both versions of macOS and both appearance modes, there are also colour changes that aren’t consistent between Sequoia and Tahoe.

Conclusions

• Appearance modes in Tahoe exhibit different behaviours from those in Sequoia, most markedly in dark mode. In this example, Tahoe has the effect of enhancing readability in dark mode.
• Colour rendering of systemOrange also differs between Tahoe and Sequoia.
• Reduce transparency has little effect other than making transparent views opaque.
• Increase contrast primarily adds black (light mode) or white (dark mode) borders to controls, but its small colour changes, as seen here in Tahoe, may impair readability.
• Designing an interface that behaves consistently in both macOS Tahoe and older versions of macOS is a challenge that may not always work out. Developers need to assess their app’s human interface thoroughly in multiple macOS, appearance modes and Accessibility settings.

There seems to be some confusion over what windmills are, so this weekend I show a selection of paintings of them across Europe. This article covers the period between 1500-1850, when they remained popular. From the twelfth century until the twentieth, they were a common sight on many skylines in northern Europe. Preceding the better-known vertical windmills were various horizontal designs, and windmills continued to flourish until the middle of the nineteenth century. Used wherever there was a need for driving a rotating axle, they were widely employed to grind cereals into flour, power sawmills, make paper, grind materials, and thresh corn.

Hieronymus Bosch’s uniquely imaginative paintings often featured realistic background landscapes. One recurring setting is a city based on Antwerp or his home town of ‘s-Hertogenbosch, with a windmill closest to the viewer. This appears in the centre panel of his triptych The Adoration of the Magi from about 1490-1500, for instance.

A similar windmill appears in a slightly different setting in the version of The Temptation of Saint Anthony now in Lisbon, from around 1500-10, in its right wing. This is shown in the detail below.

The Bruegels also worked amid many windmills, but none seems so prominently out of place than in Pieter Bruegel the Elder’s Procession to Calvary from 1564. Windmills were commonly built on hills, where they would benefit from the most consistent wind, but this example on a towering crag is not only geographically inappropriate, but completely impractical. It stands on a circular platform to allow the mill to rotate according to the direction of the wind, but would hardly have been above Jerusalem at the time of the Crucifixion.

More at home are the half dozen windmills clustered around the port of Dordrecht in the Netherlands, shown in Jan van Goyen’s View of Dordrecht with the Grote Kirk Across the Maas from 1644.

Rembrandt painted few non-narrative landscapes, but among them is this dramatic view of The Mill (1645-48) seen in the rich rays of twilight.

The great masters of Dutch landscape art like Jacob van Ruisdael must have painted many hundreds of windmills, of which one of the best-known is this view of The Windmill at Wijk bij Duurstede from about 1670. This small town, now a city, is on the bank of the River Rhine, an ideal location for delivering grain by barge, and shipping the resulting flour. This should have kept the mill as busy as the wind allowed, and its owner prosperous.

This view of a Landscape with Windmills near Haarlem was painted by John Constable in 1830, almost two centuries after the original made by Jacob van Ruisdael.

Windmills were also a common sight along the lower reaches of the River Thames. William Hogarth’s print from his Industry and Idleness series shows its anti-hero Idle being rowed out to join his ship at Cuckold’s Point on the River Thames, opposite what were then the West Indian docks, between Limehouse and Greenwich. Long after these windmills had gone, this section of the river was still involved with the grain trade.

There were other windmills upstream of the city of London too. In what must be Thomas Girtin’s most famous painting of The White House at Chelsea, from 1800, the artist looks upstream of the River Thames from a location close to the modern Chelsea Bridge. The landmarks shown include, from the left, Joseph Freeman’s windmill (or Red House Mill), a horizontal air mill, the white house close to where Battersea Park is now, Battersea Bridge, and Chelsea Old Church. Girtin painted this when he was twenty-five, and showing greater promise than his rival JMW Turner. Two years later Girtin died of asthma.

A few years later the topographic painter John Varley painted this close-up view of the same Red House Mill, Battersea, Surrey, looking back in the opposite direction.

Some of the well-known windmills supplying the city of Paris with its flour were those above its outskirts on Montmartre Hill. Georges Michel’s view of The Mill of Montmartre was probably painted in about 1820, by which time there were only a few left.

Richard Parkes Bonington probably painted Barges on a River in around 1825-6 when he was travelling near the French town of Nantes. The windmill seen behind the trees is reminiscent of seventeenth-century Dutch landscape painting.

During his detailed realist period early in his career, Johan Jongkind painted this View of Maassluis in Winter (1848). Following the long tradition of landscape painting in the Netherlands, he sets his horizon low and paints a wonderful winter sky.

Here are this weekend’s Mac riddles to entertain you through family time, shopping and recreation.

1: Well-guarded like West Berlin was, it holds your greatest secrets.

2: Motor nerve processes your images.

3: Cloth or worsted to connect it all together.

To help you cross-check your solutions, or confuse you further, there’s a common factor between them.

I’ll post my solutions first thing on Monday morning.

Please don’t post your solutions as comments here: it spoils it for others.

Inside every Intel Mac with a T2 chip, and every Apple silicon Mac, is a secure enclave, originally referred to as its security enclave. The subject of a flurry of Apple’s patents from 2012 onwards, this was introduced in the A7 chip inside the iPhone 5s and iPad mini 3, 12 years ago in September 2013, where it brought biometric authentication in Touch ID.

iPhone 5s

Protecting the most important secrets in a computer is a great challenge. No matter how secure you try to make the main processor and memory, as they’re exposed to direct attack, isolation can only be relative and temporary. An alternative approach is to move the most secure data and its processing into a secure enclave and its processor, and that’s the architectural solution chosen by Apple in what it patented as a security enclave, filed in September 2012, a year before its release in the iPhone 5s. Engineers credited for that patent are Manu Gulati, Michael J Smith and Shu-Yi Yu.

Successive iPhone chips steadily improved their secure enclaves, and by the time the iPhone 7 was introduced in September 2016, with its A10 Fusion chip, its secure enclave was handling encryption and authentication but not replay prevention. It also had EEPROM secure storage, and an AES engine with DPA protection and lockable seed bits. When the first Intel Mac with a T1 chip was released a couple of months later, that was based not on the A10 but the S2 used in the Apple Watch Series 2. The T1 thus doesn’t really have a secure enclave as such, although it supports Touch ID.

An early and thorough account of these secure enclaves was presented by Tarjei Mandt, Mathew Soling and David Wang at Black Hat USA in 2016. This appears to be the only such account apart from the section in Apple’s Platform Security Guide, most recently updated in December 2024. Apple’s engineers continued to gain new patents, covering trust zone support (filed in 2012), key management (filed in 2014), and most relevant to Macs, Pierre Olivier Martel, Arthur Mesh and Wade Benson’s patent for multi-user storage volume encryption, filed in 2020.

T2 chip

The first Macs with a true secure enclave are those with a T2 chip, starting with the iMac Pro in December 2017. Those are based on the same A10 Fusion chip from the previous year, and were already lagging the iPhone 8 in this respect.

The T2 secure enclave is another co-processor system, run by a Secure Enclave Processor (SEP), a 32-bit ARM CPU running its own operating system, sepOS, based on a specialised L4 microkernel completely different from those used by Macs and Apple’s devices. It has its own secure storage (EEPROM), and a Public Key Accelerator for signing and encryption/decryption using RSA and ECC methods. Outside the enclave is a dedicated AES256 encryption/decryption engine built into the data transfer path between the internal SSD and main system memory.

M-series chips

The big leap forward for Macs was the release of the first models featuring M1 chips, which caught up with the features of late versions (after autumn 2020) of the A12 and A13, with Apple’s second generation Secure Storage Component.

Perhaps the most significant of its improvements are measures to prevent replay attacks. Those are best illustrated with FileVault. Let’s say that you didn’t enable FileVault at first, but left your Apple silicon Mac to handle the encryption of its internal Data volume without the added protection of your password. That would mean that its volume encryption key (VEK) was generated internally by the Secure Enclave, and stored there. If you then turned FileVault on, the VEK would be encrypted using your password and the hardware key. In the T2 chip, it might be possible to use the old VEK to decrypt the volume. In the secure enclave of an M-series chip, that type of replay attack is prevented by the revocation of all previous events and records.

Other improvements include the use of second generation secure storage incorporating counter lockboxes to enforce limits on the number of passcode attempts allowed, instead of an EEPROM, and a better Public Key Accelerator.

Currently, the secure enclave is known to protect the following:

• encryption keys for Touch ID, FileVault, and the Data Protection (iCloud) keychain (but not file-based keychains);
• that Mac’s Unique ID (UID) and Group ID (GID);
• Touch ID control, and (on older devices not Macs) Face ID using a secure neural engine; in recent devices and M-series chips, that’s implemented as a secure mode in the main neural engine (ANE);
• Apple Pay handling;
• Activation Lock, through the Owner and User Identity Keys;
• signing and verification of LocalPolicy for boot environments (Apple silicon).

Communication between the CPU and SEP is performed using a dedicated mailbox whose function is detailed in Apple’s patents. Further information is also provided in the Platform Security Guide.

FileVault encryption

It has been stated widely (even here) that the secure enclave in T2 and Apple silicon chips contains a hardware encryption/decryption unit and acts as the internal SSD’s storage controller. In fact, as shown in the original patent of Martel and others, and now in the Platform Security Guide, the AES engine responsible is located outside the secure enclave, together with the Flash controller, and has a secure link to the enclave.

During SEP boot, it generates an ephemeral key to wrap keys to be used by the AES engine for encryption and decryption. That key is sent from the secure enclave to the AES engine over the dedicated connection between them, then used to protect keys transferred from the enclave to the AES engine. That ensures an unprotected key is never exposed outside the enclave and AES engine.

The Apple silicon secure enclave is by no means unique. ARM TrustZone, other Trusted Execution Environments, and Trusted Platform Modules offer similar features and facilities. However, the secure enclave is unusual because it has been integrated into all Macs with T2 or Apple silicon chips, and all Apple’s recent devices, and can’t be disabled or bypassed.

References

Manu Gulati, Michael J Smith and Shu-Yi Yu, US Patent 8,832,465 B2, Security enclave processor for a system on a chip, filed 25 September 2012, granted 9 September 2014.
R Stephen Polzin, James B Keller, Gerard R Williams, US Patent 8,775,757 B2, Trust zone support in system on a chip having security enclave processor, filed 25 September 2012, granted 8 July 2014.
R Stephen Polzin, Fabrice L Gautier, Mitchell D Adler, Conrad Sauerwald and Michael LH Brouwer, US Patent 9,419,794 B2, Key management using security enclave processor, filed 23 September 2014, granted 16 August 2016.
Pierre Olivier Martel, Arthur Mesh and Wade Benson, US Patent 11,455,432 B1, Multi-user storage volume encryption via secure processor, filed 8 June 2020, granted 27 September 2022.
Tarjei Mandt, Mathew Soling and David Wang (2016), Demystifying the Secure Enclave Processor, Black Hat USA 16 (PDF)
Apple, Platform Security Guide
Wikipedia’s overview of Apple silicon chips.

Gates as a means of access through the walls of fortified cities have ancient origins, but it wasn’t until the Etruscans and the Romans that they acquired their own deity, notably in the Roman god Janus with his two faces. His association with gates, and the start and end of war, gave rise to an interesting tradition in classical Rome: the gates at each end of an open enclosure associated with the god were kept open in times of war, and closed when the city and empire was at peace. Opening the gates of the temple of Janus was therefore a mark of starting a war.

In Rubens’ Temple of Janus from 1634, those gates, here imagined to be those of a temple, are being opened to let a warrior through to battle. Above that doorway is a statue of Janus with his two faces.

In Biblical narratives, the prominent account involving gates, other than those of heaven or hell, occurs at the start of the Passion of Jesus, in his triumphal entry into Jerusalem riding a donkey, since celebrated by Palm Sunday. This has been depicted in two significant works in the late nineteenth century.

Gustave Doré painted several versions of Christ’s Entry into Jerusalem including this preparatory sketch, in preparation for his final huge version exhibited at the Salon in 1876, measuring 6 by 10 metres.

In 1897 Jean-Léon Gérôme painted his account of The Entry of Christ into Jerusalem. According to all four gospels, Jesus descended from the Mount of Olives, and as he proceeded towards Jerusalem, crowds laid their clothes on the ground to welcome his triumphal entry into the city. Aside from being one of the major events in the Passion to be shown in paintings, for Gérôme this may have had another reading. Just a few years earlier, his paintings were being welcomed by throngs at the Salon, and commanded huge sums when sold. A short time later, his work was largely ignored, and he may have seen himself as being prepared for crucifixion in public.

The gate of hell is featured in two of the major Christian literary works of the early modern period: Dante’s Divine Comedy (c 1308-1321) and John Milton’s Paradise Lost (1667).

At the start of Dante’s Inferno, the ghost of Virgil leads the author to the gate of Hell. Inscribed above it is a forbidding series of lines leaving the traveller in no doubt that they’re going to a place of everlasting pain and tortured souls. This culminates in the most famous line of the whole of the Divine Comedy:
Lasciate ogne speranza, voi ch’intrate
traditionally translated as Abandon hope all ye who enter here, but perhaps more faithfully as Leave behind all hope, you who enter, and is seen written in William Blake’s own hand below.

It’s also William Blake who depicts Satan at the gates of hell in his paintings to accompany the second book of Milton’s epic.

Two versions, that from the Thomas set above, and below that from the Butts set, show Satan at the gate of hell, on his way out and heading for heaven.

Although the phrase pearly gates, derived from a description of the gate to heaven in the book of Revelation, has been in common use, few if any paintings have depicted them literally. However, in paintings of secular life they can have symbolic significance.

James Tissot painted The Farewells soon after his flight to London in the summer of 1871. This couple, separated by the iron rails of a closed gate, are in late eighteenth century dress. The man stares intently at the woman, his gloved left hand resting on the spikes along the top of the gate, and his ungloved right hand grasps her left. She plays idly with her clothing with her other hand, and looks down, towards their hands.

Reading her clothing, she is plainly dressed, implying she was a governess, perhaps. A pair of scissors suspended by string on her left side would fit with that, and they’re also symbols of the parting taking place. This is reinforced by the autumn season, and dead leaves at the lower edge of the canvas. However, there is some hope if the floral symbols are accurate: ivy in the lower left is indicative of fidelity and marriage, while holly at the right invokes hope and passion.

Edmund Blair Leighton’s Regency scene of The Elopement from 1893, shows a woman leaving home to run away with her lover, the oarsman in the boat. She closes the gate on her old life as she looks back and reflects, before boarding the boat in which she will start the journey of her new life.

With careful observation and a little knowledge of the startup sequence of an Apple silicon Mac, you can learn a lot about what can and can’t happen during that sequence. This article explains how, with examples from the log of a Mac mini M4 Pro.

In broad terms, startup of an Apple silicon Mac consists of the following sequence of events:

• Boot ROM, which ends in DFU mode if there’s a problem, otherwise it hands on to
• the Low-Level Bootloader (LLB) and iBoot (Stage 2), the firmware, that should end in validating and running
• the kernel, which initially runs on a single CPU core before starting others up and launching launchd, and later
• unlocking and accessing the Data volume, and progressing to
• userspace.

The opening entry in the log is the boot announcement of
=== system boot:
followed by the boot UUID. There’s then a gap of 5 seconds or more before the next entry, which marks the start of kernel boot. Those seconds are the silent phase during which the LLB and iBoot are doing their thing. They don’t write to the Unified log, but leave fragments of cryptic information known as breadcrumbs, which you can’t make use of. The kernel then writes its usual welcome of
kprintf initialized
and the following four seconds or so are filled by log entries from the kernel.

Wallclock adjustment

During this phase, the system clock is synchronised, and wallclock time adjusted, usually twice in rapid succession. This is obvious by step changes in timestamp, usually putting the clock back by several seconds in the first sync, then putting it forward slightly in the second. These play havoc with the timestamps, as you can have two or even more instances of the same time being recorded in the log. Beware of the entries
=== system wallclock time adjusted

Early during the kernel phase, it starts up all the other CPU cores in the chip, and records that in the log. Entries become progressively more varied after launchd is loaded, and this first userspace boot (without Data volume access).

Data volume unlock

With FileVault enabled, by this stage macOS still doesn’t have access to the Data volume. That means all the code run so far, and almost all the data, are immutable, locked in the firmware or the Signed System Volume (SSV). The firmware does access LocalPolicy from another container in the internal SSD, and there’s always the NVRAM, but there’s no access to anything in /Library, including the many property lists there. This also means that processes running before the Data volume is unlocked and mounted can’t write to storage.

Around 10-15 seconds after the start of booting, the login window is displayed, ready for the user to enter their password. Once that has been entered, there’s a watershed moment:
30.845097 com.apple.loginwindow Attempting to unlock the data volume <LFVolume: 0x6000001b8e40: [UUID]: Data>
30.883172 "AppleSEPKeyStore":3814:0: Sending notification for volume [UUID] unlocked (action 1, handle -842987934)
30.885459 com.apple.login volume <LFVolume: 0x6000001b8e40: [UUID]: Data> was unlocked
30.886129 com.apple.loginwindow Unlocked data volume <LFVolume: 0x6000001b8e40: [UUID]: Data>
30.886154 com.apple.loginwindow FileVault volume unlocked, allow authorization
30.887562 com.apple.loginwindowLite -[LWLSystemUnlock unlockSystem]:439: Authorization was successful
30.887587 com.apple.loginwindowLite -[LWLSystemUnlock unlockSystem]:447: logging in user hoakley
The times on those entries were deliberately delayed, as I pressed the Return key for password entry after 30 seconds had elapsed, a good 10 seconds later than I could have done so.

Shortly after that, the kernel manager shuts down, a great many kernel space processes are handed over to continue in userspace, and you’ll then see the kernel report
userspace boot

Before the Data volume is unlocked, log entries are frequent, but hardly a torrent, at around 1,000 per second, and more than 25% of them are written by the kernel. Once the kernel has booted userspace and the Data volume is accessible, log entries are written far more frequently, at an average rate of 5,000 per second, often even higher, with less than 10% of them coming from the kernel.

Phase summary

• Boot ROM, entering DFU mode or handing over to
• Low-Level Bootloader (LLB) and iBoot (Stage 2) firmware, without log entries, handing over to
• the kernel, with wallclock adjustments, until
• Data volume unlocking, then into
• userspace and access to /Library and user files.

In the nineteenth century many painters paid the bills by illustrating books, often those intended for children. Two in particular are now known as illustrators, overlooking their fine art: Gustave Doré and Walter Crane. In this series of three articles I look at the work and career of the latter, who was one of the leading children’s illustrators who shaped how children’s books would look well into the twentieth century.

Crane was also an accomplished and recognised painter, an enthusiastic fan of the Pre-Raphaelite Movement, a close friend of William Morris, a key member of the Arts and Crafts movement, and an overt and active Socialist.

He started his training as an apprentice to the wood-engraver William James Linton, between 1859 and 1862. In 1863 Edmund Evans employed him to illustrate ‘toy books’ for children, and he continued to create book illustrations until well after 1900. In the later years, he extended his repertoire to include special editions of the Faerie Queene, a volume of Arthurian legends, and a book about the New Forest.

His career in painting had started slightly earlier, though, when his first work was accepted by the Royal Academy in 1862, and he continued to paint independently of his illustrations.

Crane was one of the first artists to base a painting on Alfred Lord Tennyson’s (1809–1892) poem The Lady of Shalott, published in 1833 and 1842. This tells part of the Arthurian legends, that of Elaine of Astolat, as given in an Italian novella from the 1200s.

The Lady of Shalott lives in a castle connected to Camelot by a river. She’s subject to a mysterious curse confining her to weaving images on her loom, and must not look directly at the outside world. One day, while she sits and weaves, she catches sight of the knight Lancelot. She stops weaving and looks out of her window directly towards Camelot, invoking the curse. She abandons her castle, finds a boat on which she writes her name, then floats downriver to Camelot, dying before she arrives. Lancelot sees her body, and the poem ends:
But Lancelot mused a little space
He said, “She has a lovely face;
God in his mercy lend her grace,
The Lady of Shalott.”

Crane’s Lady of Shalott from 1862 shows her white in death, laid out in her boat, tresses and flowing sleeve draped over its gunwhales into the still water at the river’s edge. This is set in an ancient wood, in dramatic twilight, presumably dusk. This painting was accepted for exhibition at the Royal Academy, and must have influenced JW Waterhouse’s much better-known version just over 25 years later (below).

The following year he chose a story from the Old Testament. According to various sources in the Bible, Boaz was a wealthy landowner in Bethlehem who noticed Ruth, a widow in such difficult financial circumstances that she came to glean grain from his fields. Boaz invited her to eat with him and his workers, and started deliberately leaving grain for her to glean. Because they were distantly related, Ruth then asked Boaz to exercise right of kinship and marry her. They had children, and David was their great-grandson.

Crane’s painting, which is in oils despite resembling a watercolour illustration, shows the couple at the end of lunch, during Ruth’s gleaning. Their dress is an odd composite of the Biblical and Arthurian. She is looking down at her hands, as if contemplating grain held in her left palm. He has turned and looks towards her. In the background Boaz’s workers continue the harvest, and saddled horses are idle, a castellated house set in the crag behind them.

Two years later he was one of the first artists to depict John Keats’ ballad of La Belle Dame Sans Merci, written in 1819, and later revised slightly. It gives a simple story of love and death, including the verses:
I met a lady in the meads,
Full beautiful, a fairy’s child;
Her hair was long, her foot was light,
And her eyes were wild.

I made a garland for her head,
And bracelets too, and fragrant zone;
She looked at me as she did love,
And made sweet moan.

I set her on my pacing steed,
And nothing else saw all day long,
For sidelong would she bend, and sing
A faery’s song.

The ‘belle dame’ of the title is shown riding side-saddle on the knight’s horse, flowers in her long, flowing tresses, and the knight, clad in armour and heraldic overgarments, holds her hand. This appears to have inspired later paintings by Arthur Hughes and Frank Dicksee.

There’s some dispute over whether this triptych from about 1870 shows The Danaïdes, or Europe, Asia, Africa, or maybe both. The fifty daughters of Danaus were forced to marry the sons of their uncle Aegyptus, but their father told them to kill their husbands on their wedding night. All but one followed his instructions, for which they were condemned to eternally carry water in leaking vessels. Alternatively, the woman on the left could be African, that on the right Asian, and the woman in the middle European.

Crane married in 1871, and the couple travelled in Europe for the next two years. They visited Florence where they must have seen some of Botticelli’s paintings.

Botticelli’s The Birth of Venus (c 1486) is one of the world’s most famous paintings, and shows the goddess Venus, when she was born from the waters as an adult, arriving at the shore.

Crane bases his Renaissance of Venus (1877) on Botticelli’s painting, and links her rebirth back to the Renaissance. She is stood at the edge of a placid sea, the water just above her ankles. Three attendant graces are also getting out of the water in the middle distance, but appear to have been bathing. A train of white doves flies down and behind Venus, to start landing on the shore at the right. In the distance are the remains of a classical building at the water’s edge, and what appears to be a section of Mediterranean coastline. Further out at sea, a sailing boat passes by. Crane painted this in tempera, just as Botticelli did.

In classical Greek mythology, Persephone, daughter of Zeus and Demeter, is the queen of the underworld. She acquired that role when Hades, god of the underworld, was overcome with love and lust from one of Cupid’s arrows, and had seen Persephone picking flowers with friends. Hades then abducted her to be his queen.

Crane’s Fate of Persephone from 1878 shows her at the moment of abduction. She had been picking spring flowers in the meadow with the three other women shown at the left. Hades brought his chariot, complete with its pair of black horses symbolising the underworld, and is seen gripping Persephone’s right arm, ready to move her into the chariot and make off.

It’s remarkable that, although their body language is emphatic and clear, each of the five figures has a completely neutral facial expression. This helps its appearance as a frieze, an effect enhanced by Crane’s use of oil and tempera. The horses appear in complete contrast, champing at their bits and poised to set off at a gallop.

The following year he’s believed to have painted this elaborate setting of George Howard, 9th Earl of Carlisle, and Rosalind, Countess of Carlisle, seated in the gardens at Naworth Castle, Cumbria, with a companion, standing holding a book. However, it was later signed clumsily by “E Burne Jones”, possibly in an attempt to pass it off as a more valuable work.

This couple had married in 1864, and were ardent supporters of the Pre-Raphaelite Movement, and friends of Crane since they were both students, Edward Burne-Jones and William Morris. Howard was an accomplished painter who had trained at Heatherly School of Fine Art in London, and later became a trustee of the National Gallery in London.

Edward FitzGerald’s translation of a selection from the poetry attributed to Omar Khayyam (1048-1131) was published in 1859, was popularised from 1861, and appreciated by several of the Pre-Raphaelite Movement. Walter Crane’s painting from 1882 was accompanied by the following quotation from FitzGerald’s Rubaiyat:

Would that some winged angel ere too late
Arrest the yet unfolded Roll of Fate,
And make the stern recorder otherwise
Enregister, or quite obliterate!

Ah love! could you and I with him conspire
To grasp this sorry scheme of things entire,
Would we not shatter it to bits – and then
Remould it nearer to the heart’s desire!

A male winged angel is on bended knee before the figure of Time, who holds his scroll recording the destiny of all mankind. The angel’s hands are intertwined with those of Time: both right hands grasp the quill used to record destiny, both left hands are at the other end of the scroll. The angel looks up pleading at Time, but Time looks down at him with a frowning scowl. In front of the dais on which the angel kneels and Time sits is an hour glass. The whole is set inside a circular building revealing the stars through its roof, like a planetarium.

Endymion was a classical Greek mythological character, an Aeolian shepherd. Although accounts differ, some tell that Selene, Titan goddess of the moon and in Roman terminology, Diana, fell in love with Endymion, when she found him asleep one day. Selene asked Zeus to grant him eternal youth, resulting in him remaining in eternal sleep. In spite of his somnolence, she still managed to have fifty daughters by him. In Crane’s beautiful pastoral watercolour of Diana and Endymion from 1883, he is fast asleep in a meadow. Diana is in her hunting role with her dogs, bow and arrows. Endymion’s flock of sheep is in the distance.

References

Wikipedia

O’Neill M (2010) Walter Crane. The Arts and Crafts, Painting, and Politics, 1875-1890, Yale UP. ISBN 978 0 300 16768 9.

Local Spotlight search problems appear common, and are all too often tackled blindly by forcing a volume’s indexes to be rebuilt. Although that can sometimes resolve the problem, without knowing what its cause is, it can just waste time and effort. Indeed, in some cases rebuilding the indexes can worsen the problem, at least temporarily. This article explains how you can use SpotTest 1.1 to perform systematic testing and arrive at a diagnosis before hazarding a guess at what the treatment should be.

1. Spotlight settings

Before opening SpotTest, check that Spotlight settings are in order, and don’t exclude the volume or folder you’re trying to search, or the document type you’re looking for. Then open Activity Monitor and watch its CPU % listing to verify that Spotlight isn’t currently in the process of reindexing or performing other maintenance to its indexes. If it is, delay testing until those have completed. Searching using Spotlight while it’s actively working on its indexes will give odd results, or none at all.

If you’re going to use SpotTest on any location with privacy control, such as your Home Documents folder, or an external disk, consider adding the app to the Full Disk Access list in Privacy & Security settings, before opening it.

2. Home folder test

Even if your interest is in a different volume, you should perform a basic test of a new test folder in your current Home folder, to establish a baseline and confirm that Spotlight is working there.

Open SpotTest and set it to defaults, with a Term of cattle, a Scope of [Home], and both Search Keywords and Search EXIF ticked.

Click the Create Tests tool (the leftmost of the tools) to create the folder of test files at the top level of your Home folder. Make a note of the time you do this to the second.

About 10-15 seconds after that, click either the Run NSMetadata test or Run mdfind test tool. You should then see a list of files found, including those in the test folder ~/0_SpotTestFiles, including A, B, C, D, E, F, G, K, L, M

If you don’t see those listed, open Mints and use the Log Window button in its Spotlight section to obtain a log extract from the time the test files were created, or use LogUI to do the same. You’ll then need to look at that log extract to see if there are clues as to why indexing didn’t take place in the period.

Leave the test folder where it is, and anything from 1 hour to 2 days later, repeat the search using either or both of those tools. Once additional indexing has been undertaken:

• NSMetadata should now find A, B, C, D, E, F, G, I, K, L, M but not H
• mdfind should now find A, B, C, D, E, F, G, H, I, K, L, M.

I is found by the Live Text process, and H by Visual Look Up, the latter only being found by the mdfind search.

These tests have demonstrated:

• mdworker and mds indexing of files supported by system mdimporters;
• delayed background mediaanalysisd image analysis and mds indexing of Live Text and Visual Look Up content.

To match test files with their importers, click the Check importers tool. Note that file L doesn’t use a plugin, and N uses a plugin but can’t be found because the search term is inside an image in the PDF document, which currently isn’t recoverable content.

3. Custom mdimporter

Many apps come with their own custom mdimporter that provides Spotlight indexing support for document types not supported by macOS. In the past, these were normally installed in /Library/Spotlight, but more recent apps typically keep them inside the app bundle in Library/Spotlight. These can be tested easily.

Create and save one of those custom document types, so that it contains the word cattle in a way that should be searchable by Spotlight. Copy that document to the ~/0_SpotTestFiles folder, wait 10-15 seconds, then repeat the test search. You may well notice that NSMetadata search doesn’t find your custom test document, but mdfind does. This is because of the difference in the search criteria they use.

You should also click the Check importers tool to check that the correct mdimporter was recognised and used for the custom document type.

4. Volume test

If Spotlight works correctly with the test folder in your Home folder, you may wish to progress to testing a different volume or location. Having created its test folder in ~/0_SpotTestFiles, copy that to the other location. Before you try to change the Scope of the search, click on the button to list available volumes, then select the volume containing the copied test folder in the Scope menu.

When you perform the two types of search on that volume, the same rules should apply as to which will be found. Note though that finding files I and H can take much longer, or they may not appear at all.

5. Search term test

When you’re confident that a search term of cattle can be found reliably, you may wish to extend your testing to other terms. Take care when choosing custom terms, as you want to be confident that they should be found, but not in such numbers that the results are overwhelming. You will also need to create your own test files containing the custom term.

Diagnosis

SpotTest can thus provide key information on:

• delay or absence of find following creation of test files. If no indexing activity is seen in the log, that suggests indexing failure. If the test files are indexed promptly, it suggests search failure;
• delay or absence in finding files H and I, indicating an indexing failure;
• failure of a custom mdimporter to index a custom document type;
• failure to index another volume.

Those should fit in with the overall scheme used by Spotlight, as shown below.

Happy hunting!

Another of the new genres to emerge and develop in the Dutch Golden Age is animal painting. This appears to have started among Flemish painters at the end of the sixteenth century, but didn’t become popular until about 1640, when a succession of painters in the Dutch Republic depicted domestic animals as part of their landscapes.

Aelbert Cuyp is thought to have painted this Landscape with Cattle when he was only about nineteen, in 1639. It’s set against the background of the city of Dordrecht, the oldest in the two provinces of Holland, and situated on the Rhine-Meuse-Scheldt river delta. The herdsman and animals in the foreground are engaged in diversions from that landscape: the man is taunting a billy goat, while the cow at the far right is urinating copiously.

Cuyp continued to develop his landscapes with more diverse themes. Orpheus with Animals in a Landscape from about 1640 is one of at least two different paintings he made of this story from mythology. Here he has included a wide range of both domestic and exotic animals and birds, including a distant elephant, an ostrich, herons and wildfowl.

His paintings of domestic animals also took him indoors, for example in this fascinating painting of Sheep in a Stable from about 1645. The sheep are faithfully depicted, and surrounded by objects suggesting elements of a still life. In the foreground are empty mussel shells, a couple of earthenware pots, and two wickerwork baskets with some scarlet cloth. He also renders the texture of the fleeces using painterly brushstrokes, particularly that of the standing ram.

Artists who had travelled to lands in the growing Dutch Empire sent back paintings of the animals they saw there. Albert Eckhout, who had been born in Groningen, accompanied John Maurice, Prince of Nassau-Siegen, Dutch governor of Brazil, when he landed at Recife in January 1637, to document local inhabitants and wildlife.

Eckhout’s Study of Two Brazilian Tortoises is believed to have been painted in Brazil in about 1640.

Paulus Potter was probably the first dedicated animal-painter, through his brief career in Delft, The Hague and Amsterdam.

Potter’s first masterpiece is The Bull (also widely known as The Young Bull) (1647), which is nearly life-sized, and almost hyperreal in its surface details. Originally intended just as a portrait of the central bull, Potter enlarged the canvas to accommodate (from the left) a ram, lamb, ewe, herdsman, cow, and above them a bird of prey, possibly a buzzard. Beyond them are more cattle in the meadows, which recede to the church of Rijswijk, which is between Delft and The Hague.

He went on to paint portraits such as Two Pigs in a Sty (1649), featuring two hairy pigs at rest. Many of the older breeds of pig were more hirsute than modern varieties, and Potter has painted their coats realistically, as well as skilfully lighting the face of the sow sat on her haunches.

Potter’s Cows Grazing at a Farm from 1653 was one of his last paintings, and apart from its meticulous detail, its rich lighting effects might be more typical of Corot two hundred years later. Potter died tragically young the following year, but the new sub-genre was taken up by others, including Adriaen van de Velde.

Van de Velde’s undated Milkmaid with Cow and Goats in Front of a Barn is a farmyard delight, with the cow being milked looking directly at the viewer.

The Hut (1671) was one of van de Velde’s last paintings, and has long been esteemed in the Netherlands. It’s one of his most natural compositions, sparkling with bright colour in the clothing and animals. The artist even adds the reality, perhaps as a touch of humour, of some fresh cowpats.

Jan Weenix’s early painting of a Landscape with Shepherd Boy from 1664 reveals his true forte in the realistic depiction of the sheep and dog.

Some specialised even further: Melchior d’Hondecoeter concentrated on birds and game.

Concert of the Birds (1670) is one of his more elaborate paintings featuring a wide range of native species.

D’Hondecoeter painted this huge Portrait of Three Children in a Landscape with Game in the latter half of the 1600s. The children appear to have taken to field sports at a very early age, and have here amassed an impressive ‘kill’, with their muzzle-loading gun, although I hope that an unseen adult may have had a hand in its use. The lone tortoise being ignored by each of the children and dogs is slowly crawling its way towards them, as if it has just emerged into the wrong painting.

DropSum is my simple drag-and-drop utility for checking MD5 and SHA256 hashes, and using them to compare pairs of files to see if they’re identical.

This new version brings two changes:

• Text entered in its two text boxes, where you paste hashes, is now cleaned of any spaces and hyphens, and set in lower case, before being used as a hash, although it’s not altered in the text box. This should save you having to edit what you paste there. Thanks to Panda for requesting that.
• I have tried to improve readability when in dark mode in Sequoia and earlier. Thanks to EcleX for requesting this.

That said, the window’s appearance is a compromise between what looks best in Sequoia, and that in Tahoe. To see what I mean, here’s the same app, in its new version 1.2, in two versions of macOS, both in dark mode with Reduce Transparency enabled.

In macOS Tahoe there’s strong contrast throughout, and all text is readable, as it is in light mode.

Yet in macOS Sequoia, white text in unselected text boxes is shown against its orange background, rather than grey or black.

I have a feeling we’re in for an autumn of similar visual discrepancies appearing in other apps, whether or not they’ve been built for compatibility with Tahoe.

DropSum 1.2 for Big Sur and later, including Tahoe, is now available from here: dropsum12
from Downloads above, and from its Product Page.

Its MD5 hash is 9370f006d65eb3f6f65ab97dc78ce345
and SHA256 is f898b580138dc05d273c8b7f16321ad6d6754d76ecabf1c49fcac1d32bc156e6

Enjoy!

Apple has just released its weekly update to XProtect for all supported versions of macOS, bringing it to version 5312. As usual, Apple doesn’t release information about what security issues this update might add or change.

This version adds three new detection rules: MACOS.SOMA.AUENB augmenting rules for the Soma/Amos family, MACOS.DUBROBBER.CHBI for another Dubrobber variant, and MACOS.ODYSSEY.LELI for an additional Odyssey variant.

You can check whether this update has been installed by opening System Information via About This Mac, and selecting the Installations item under Software.

A full listing of security data file versions is given by SilentKnight and SystHist for El Capitan to Tahoe available from their product page. If your Mac hasn’t yet installed this update, you can force it using SilentKnight or at the command line.

If you want to install this as a named update in SilentKnight, its label is XProtectPlistConfigData_10_15-5312

Sequoia and Tahoe systems only

This update has now been released for Sequoia via iCloud. If you want to check it manually, use the Terminal command
sudo xprotect check
then enter your admin password. If that returns version 5312 but your Mac still reports an older version is installed, you may be able to force the update using
sudo xprotect update

In the long-distant past, our ancestors discovered that processing some natural products created glues. The raw materials either came from boiling animal bones, hide, and other offal, or from natural exudates of plants, and these came to be used as the binder for paints. Being ancient in origin, different combinations of binder, pigment, and other substances developed, and those have left a confusion of terms, including glue tempera, and distemper. These represent a spectrum of paints, ranging from those using only glue and pigment, to others also incorporating substantial amounts of powdered chalk or lime to increase their opacity, and related to whitewash.

Glue tempera was used in antiquity, and outside Europe remains in widespread use. It has several disadvantages for the painter, including:

• ‘Drying light’; as the paint dries, so it undergoes marked colour change, reducing the intensity of chroma.
• Mechanical fragility of the paint layer, which is particularly susceptible to abrasion and/or cracking.
• Solution on re-wetting, so that glue tempera can easily be reworked like watercolour, but is unsuitable for exposure to water or damp. Hardening of the glue binder isn’t the result of a stable polymerisation as with oil paints, and can readily be reversed.
• Relatively poor protection of light-sensitive pigments, resulting in some fading over time.

Taken together these mean that what we see in glue tempera paintings today is often quite different from how they looked at the time they were painted.

In the early Renaissance, some artists used glue tempera extensively and with great success, although surviving works haven’t aged as well as those painted using egg tempera or oils.

Dieric Bouts’ The Entombment from about 1450 was painted using glue tempera on linen. As it’s now well over half a millennium old its colours have faded, but it remains worth seeking out when you next visit The National Gallery in London.

In the south of Europe, Andrea Mantegna was one of its great exponents, as shown in his marvellous glue tempera and gold painting of A Sibyl and a Prophet from about 1495. Because this is monochrome and uses gold as the pigment, this has neither changed colour nor faded.

Some artists, such as Joris Hoefnagel, continued to use these ancient techniques, as shown in this painting of Diana and Actaeon from 1597. This is finely executed in glue tempera and gold on vellum, and its colours have survived well.

With the widespread adoption of oil paint, glue tempera almost disappeared until it was revived at the end of the eighteenth century by William Blake.

Blake painted a series of major works in what he termed tempera, using glue as their binder. This Adoration of the Kings from 1799 shows the dulling of colour and fine cracking from his use of stretched canvas as its support.

Some of Blake’s glue tempera paintings have survived in better condition: The Christ Child Asleep on the Cross, or Our Lady Adoring the Infant Jesus Asleep on the Cross from 1799-1800 has fared better, retaining more of its original colour.

Paintings such as Blake’s Virgin and Child in Egypt from 1810 show the fine modelling he was able to achieve in its figures. Overall, though, the condition of his glue tempera paintings isn’t good. It has been suggested that some of their variation is attributable to different sources of glue, clearly of major importance. For a long time, glues provided for this and similar purposes in painting have been referred to as rabbit skin glue, but in reality the great majority have been derived from a wide range of animal products, often in uncontrolled conditions.

After Blake, the medium fell back into obscurity until later in the nineteenth century, when it was revived by movements attempting to return to techniques of the past, most prominently the Nabis in France.

Pierre Bonnard used glue tempera early in his career, when painting this exquisite three-panelled Japoniste screen of The Stork and Four Frogs in about 1889, as the Nabis were forming. Using more modern pigments, Bonnard has achieved high chroma, comparable to anything in oils, and quite unlike traditional glue tempera.

Odilon Redon experimented with glue tempera in his painting of Buddha from 1904.

Édouard Vuillard used glue tempera in many of his paintings both during his Nabi period and later, for example in this view Under the Trees of the Red House from about 1905.

Vuillard’s At The Pavillons in Cricqueboeuf. In Front of the House, from 1911, shows how effective the medium can be.

Vuillard continued to use glue tempera in his late realist paintings, such as Morning Concert, Place Vintimille from 1937-38, showing a trio of friends playing for the artist in his Paris apartment.

Glue tempera remains in use today by a very few artists, who at least have a wider range of lightfast pigments to choose from, and more consistent formulations of glue to act as binder.