Sirens are mythical woman-like creatures with alluring voices, best-known from their appearance in Homer’s Odyssey, but also featuring in other tales including that of Jason and the Argonauts. Typically their singing lures sailors to their death, and that reputation has led them to represent anything that’s dangerously attractive. Originally they weren’t described in any physical detail, but visual representations soon envisaged them as having the upper bodies of beautiful young women, and the lower bodies and legs of birds, and that has been incorporated and elaborated in later accounts and retelling.

At the end of the year that Odysseus and his crew stayed with the sorceress Circe, she helpfully advised him that he would have to sail past the sirens, two to five creatures who lured men to their death with their singing. In preparation, Odysseus got his sailors to plug their ears with beeswax before they reached the sirens, so they couldn’t hear their song, and to bind him to the mast. He gave them strict instructions that under no circumstances, no matter what he said at the time, were they to loosen his bonds, as he would be listening to the sirens’ song.

As the group reached the sirens, Odysseus told his men to release him, but instead they bound him even more closely to the mast. Once they had passed safely from earshot of the sirens, Odysseus used his facial expression to inform his men, who then released him, and they sailed on.

William Etty’s The Sirens and Ulysses from about 1837 is one of the pioneering accounts in paint of this story from the Odyssey. His three naked sirens are all woman, one playing a lyre, another holding double pipes aloft, all three doing their best to draw the sailors from Odysseus’ ship to a shore where there are the remains of earlier victims.

Edward Poynter’s The Siren from about 1864 has Aesthetic overtones in the lyre she is playing.

Arnold Böcklin takes an unusual approach of almost dereferencing Odysseus in his painting of Sirens from 1875, although there is an approaching vessel that could be his. The two sirens filling the canvas are very human down to the waist, below which they resemble birds. One sits facing us, clearly in full voice, and highly alluring in looks. The other, her back towards us, is playing an aulos and looks rather obese, to the point of almost being comical, her right breast laid upon a flat-topped rock. At their feet are three human skulls and other bones to indicate their graver intentions.

Gustave Moreau’s The Sirens (1882) shows them as beautiful figures in a static scene, with a saturnine setting sun. There is, though, a lone sail on the horizon that hasn’t yet attracted their attention. Their lower legs turn into the writhing coils of sea serpents.

Moreau’s slightly later group portrait of The Sirens from about 1885 is more complete, with Odysseus sailing past, but its three figures are clearly all woman and no bird.

Eight Dancing Women with Bird Bodies (1886) is one of Hans Thoma’s unusual mythological paintings. The best-known women with bird bodies were the sirens, who range in number from two to five. In another painting showing the sirens trying to lure a passing ship, Thoma paints similar figures, suggesting these are intended to be sirens.

John William Waterhouse’s Ulysses and the Sirens (1891) is closer to the Homeric account, although he provides a total of seven sirens, shown as large eagle-like birds of prey with only the head and neck of beautiful women. He has added bandage wrappings around the head of each sailor to make it clear that their ears are stopped from hearing sound, a visual device that links neatly with the text. His sirens are clearly singing, particularly the one closest to the viewer, who is challenging the hearing protection of one of the sailors. Another sailor, at the stern of the ship (left of the painting), is seen clutching his ears.

Almost a decade later, Waterhouse painted this non-narrative portrait of The Siren (1900).

The Sirens (1903) marked Henrietta Rae’s return to painting narrative works featuring classical nudes. Odysseus’ ship is in the distance, as three beautiful sirens use their aulos and lyre to lure its occupants.

Late mythology suggests an unpleasant end for these sirens: Hera challenged them to a singing contest against the Muses. When the latter won, the penalty they exacted of the sirens was to have all their feathers plucked out to turn into crowns. As a result of that disgrace, the sirens turned white, fell into the sea, and formed the islands including modern Souda, on the north-west coast of Crete in the Mediterranean.

Sirens have steadily spread their presence into other paintings, particularly during the twentieth century.

Georg Janny’s fantasy painting of Sirens Bathing by the Sea from 1922 is throughly other-worldly, and there’s no trace of their bird legs.

More cryptic is Paul Nash’s Surrealist Nest of the Siren (1930), which brings together the incongruous, and hardly refers to Homer’s story. The painting is framed by brightly-painted walls with pillared decorations, perhaps ornate wainscot panelling. In the middle of these is what might be a painting, but also seems to be a three-dimensional plant trough containing sinuous shrubs. In the middle of those is a small nest, like an acorn cup.

Standing in front of this is a structure resembling a weather-vane, mounted on a turned wooden shaft. At the weather end of the vane is the faceless figure of a siren; the leeward end appears purely decorative. Three red rods appear to have detached themselves from the walling, two protruding from the plant trough, the third resting on the floor.

They even manage to sneak symbolically into other classical stories.

In Girodet’s ink and chalk drawing of The Meeting of Orestes and Hermione (c 1800), Hermione is seen at the right, her arms folded, looking coy as Orestes approaches her. The second woman, with Orestes, is presumably Hermione’s maid. This is one of a series of illustrations made by Girodet to accompany Racine’s play, and has subtleties you might expect from a great narrative artist. Visible in the gap between the figures is a table-leg in the form not of a Fury foretelling Orestes’ fate, but of a siren, implying that Hermione is luring Orestes to her. Hermione, for all her apparent coyness, has let the right shoulder-strap of her robe slip, in her enticement of Orestes. She has assumed the role of femme fatale, as portrayed by Euripides and Racine.

In more recent literature, sirens appear in the less-known second part of Goethe’s play Faust.

Margret Hofheinz-Döring is one of the few artists who has painted from this second part. With the Sirens from 1962 is her pastel painting showing the sirens among rocky inlets of the Aegean Sea, a sub-scene concluding the second act.

If you have updated your Mac to Tahoe 26.1, you may be blissfully unaware that it will now automatically download and install some security updates, regardless of its Software Update settings. Open Privacy & Security settings, scroll down to the end and you’ll see a new item, Background Security Improvements, that Apple has kindly turned on for you. There are matching new settings in iOS and iPadOS 26.1 that are also enabled by default.

Apple seemingly forgot to mention these when listing the changes in 26.1, and its documentation of these Background Security Improvements (BSI) is sketchy to say the least. However, the description there as “lightweight security releases for components such as the Safari browser, WebKit framework stack and other system libraries” is so similar to that for RSRs as “improvements to the Safari web browser, the WebKit framework stack, and other critical system libraries” that we can only conclude the BSI is a rebranded RSR.

What is an RSR/BSI?

Although almost all of macOS is contained in the System volume, turned into a snapshot that’s protected by a tree of hashes with a signature, then mounted as the Signed System Volume, there are additional components that are delivered in separate cryptex files. These are also heavily protected with signatures to verify their contents, and are mounted well after the kernel has booted. APFS then grafts them into the root file system so their contents appear in the correct places. There are currently two main cryptexes common to all Macs, one containing Safari and its WebKit components, the other with dyld caches supporting frameworks. Apple silicon Macs additionally have many smaller cryptexes to support AI and related features.

Because those cryptexes are separate from the SSV, they can be unloaded, replaced with updated versions, and reloaded without necessarily having to reboot the kernel, or go through any of the complex procedures to update macOS itself. Apple first tested this new type of update, a Rapid Security Response (RSR), in beta-releases of macOS 13 Ventura, and the first was publicly released for Ventura 13.3.1 on 1 May 2023.

How do RSRs work?

RSRs have been released using the regular Software Update mechanism, controlled in its settings, and can be uninstalled manually even if you have opted for them to be installed automatically.

To remove an RSR, you open System Settings > General > About, and look down for the macOS version. At the right of that line is an ⓘ button: click on it to see the dialog above, allowing you to uninstall it.

Why don’t we get RSRs now?

Apple proudly announced RSRs at WWDC in June 2022, and they were listed among the new features in Ventura: “Get important security improvements to your devices even faster. This isn’t a standard software update. These improvements can be applied automatically between normal updates — without a restart.”

Although the first in May 2023 seemed to go well, the next on 10 July was an embarrassing disaster. RSR 13.4.1 (a) fixed one WebKit vulnerability, but unfortunately it also changed the version number of Safari to 16.5.2 (a), which was reflected in its User Agent, so broke access to many popular websites including Facebook. That had to be rectified in RSR 13.4.1 (c) released three days later. And all three of these RSRs required the kernel to be rebooted after their installation.

Since then, as far as I’m aware, Apple hasn’t released any further RSRs, although they’ve still been referred to throughout its documentation.

Their greatest limitation is that they can only fix vulnerabilities that are confined to Safari, WebKit and other components that are delivered in cryptexes. More commonly, urgent security patches also require changes to software in the SSV, for which the only solution is a full update. For example, during the year that macOS Sequoia was current, it received six patch updates in between those scheduled. Of those, only two might have been suitable as RSR/BSI updates, as all the others required changes to the SSV.

How do BSIs work?

If Apple’s current account of BSIs is complete, the only control we have over them is whether they’re downloaded and installed automatically. If you opt for that, as Apple has set as the default, then you won’t be given any warning, or even informed when the BSI has been installed on your Mac. The only way you’ll be able to learn that is by trawling through the list of software installations in System Information, although Apple will post information about the BSI in its security release notes, following its release.

If there’s a problem with a BSI, such as that in the second RSR in July 2023, then there’s no option to uninstall the BSI and revert to a previous version of that cryptex, as there was with RSRs. However, Apple might decide to remove the BSI from your Mac.

Given the short and unfortunate history of RSRs, that might appear surprising.

A glance at a map of the Dutch Republic during its Golden Age reveals that very little was far from the sea, or one of the large rivers that flow through its countryside and cities. In the middle was the Zuiderzee, a large inland sea only kept at bay by a great many dikes.

With the popularity of landscape painting, it was inevitable that the sea, rivers and other bodies of water became a common feature in those views. This article shows a small selection from some of the most famous artists of the time.

Jan van Goyen’s View of Dordrecht with the Grote Kirk Across the Maas (1644) shows a familiar view of the city, with particular interest in its buildings. Its skyline is dominated by the still-unfinished 65 metre tower of the Grote Kerk, built between 1285-1470. There are many small boats at work on the choppy water, here depicted in an older fashion similar to works from the Renaissance.

Aelbert Cuyp’s View on the Rhine from the following year appears to have been the result of a trip up river, into steeper terrain inland. It is wonderfully sketchy, and might even be mistaken for one of Turner’s landscapes from nearly two centuries later. In the Netherlands, the lower reaches of this river form part of the great Rhine–Meuse–Scheldt delta, which includes both the major port and city of Rotterdam, and Dordrecht.

Inevitably, many of Cuyp’s finest landscapes show his home city, such as this View of the Maas at Dordrecht from about 1645-46. This makes best use of an extreme panoramic panel, now commonly used for such marine landscapes.

Cuyp also painted a few marine nocturnes, including this view of the Sea by Moonlight from about 1648, where he extended his exploration of the effects of light.

Philip de Koninck’s Wide River Landscape from about 1648-49 refers to a wide landscape rather than river, I believe. All seems at peace in the countryside, with livestock in the field in the foreground, and a small boat making its way under sail along the river.

Although Cuyp never seems to have become a more dedicated marine specialist, his paintings of ships including The Passage Boat from about 1650, are landmarks at the height of his career. Passage boats were those engaged in regular ferry trips between set ports, in this case probably Dordrecht and Rotterdam, a distance of little more than twelve miles (20 km) by water. With the Republic’s extensive networks of rivers and canals, these were a popular means of transport at the time. The figures in the boat are finely detailed, and include a drummer towards the stern.

At their best, Cuyp’s coastal landscapes, such as The Maas at Dordrecht from about 1650, are full of rich light, earning him the title of the Dutch Claude Lorrain. This shows another passage boat packed with passengers, together with its drummer.

Salomon van Ruysdael’s View of Alkmaar from the Sea (c 1650) is unusual in showing such a flat coastal landscape on a panel orientated not in landscape mode, but in portrait to include its fine cloudscape.

Cuyp’s grand view of The Valkhof at Nijmegen from about 1652-54 shows the Imperial castle that was to be demolished in 1798, on its small hill beside the river. The landscape is bathed in golden light, and broken clouds are tinged with similar Claudean colour as they drift through its lucent sky.

Jacob van Ruisdael’s The Shore at Egmond-aan-Zee from about 1675 was painted to the west of Alkmaar, on the North Sea coast in North Holland, with its stormier weather.

De Koninck’s River Landscape from the following year shows a single oarsman taking a small group of people along the river.

Many of de Koninck’s panoramas are painted on panels or canvases of normal proportions, and just look wide. Flat Landscape With a Broad River is more unusual for his use of a proper marine format. It also appears more sketchy, and has little staffage, as if it may even have been painted in front of the motif.

When Apple released macOS 26 Tahoe I published an article exploring how you can configure its redesigned interface, using its additional variations to appearance modes and its new Liquid Glass effects. When Tahoe 26.1 was released a couple of days ago, it changed those by adding a new control for those Liquid Glass visual effects. This article shows how that might change your options.

There are now four sets of controls:

• Appearance mode, Light or Dark, in Appearance settings;
• Liquid Glass setting, Clear or Tinted, in Appearance settings;
• Display variations to Reduce transparency or Increase contrast, in Accessibility settings;
• Icon & widget style, in Appearance settings.

Apple’s descriptions of the two states for Liquid Glass read:

• “Clear is more transparent, revealing the content beneath.”
• “Tinted increases opacity and adds more contrast.”

Those terms indicate an overlap with Accessibility settings. However, if either of the Accessibility settings is enabled, then the Liquid Glass setting is unavailable. I also presume that the word tinted here refers to the faint colouration that might be seen in what would otherwise be a transparent view, rather than any more generalised addition of colour.

Light mode

There are four overall variations of light mode, depending on Liquid Glass and Accessibility settings.

The starting point and default is in light mode, Liquid Glass clear, without Accessibility, and icon & widget style set to Default. Note the effects of transparency on the menu bar, widgets, the Liquid Glass effect in the left side of the Dock, and the upper row of icons in the Finder window. If you like those, you don’t have to change any settings.

This is the same, but with Liquid Glass set to Tinted. I’m unable to see any difference between those settings in this example.

This is light mode with Reduce transparency enabled in Accessibility settings. This disables all Liquid Glass effects and restores the traditional menu bar and Dock. The effect on Desktop widgets is perhaps less beneficial.

In light mode with Increase contrast (automatically coupled with Reduce transparency) enabled, the predominant effect is the outlining of controls within each window, rather than any change in contrast. Colours used by the system, such as the traffic light controls at the top left of each window, and those in themes, are darker, but those elsewhere, as in icons, aren’t changed. The effect here is to make controls clearer rather than actually changing contrast.

Dark mode

Without changing Accessibility and leaving Icon & widget style set to Default, and Liquid Glass set to Clear, dark mode shows transparency and Liquid Glass effects as you expect. These are again most visible in the menu bar, Dock, and the upper row of icons in the Finder window.

This is the same, but with Liquid Glass set to Tinted. Two most obvious differences are seen in the back-forward controls by the title of the Appearance settings, which oddly appears white, and the widgets, which are much darker. There are some inconsistent differences in the toolbar of the Finder and Tips windows, but they are more subtle.

With Reduce transparency enabled in Accessibility settings those transparency and Liquid Glass effects are removed.

Enabling Increase contrast outlines controls clearly, but any changes in system colours are more variable than in light mode.

Icon & widget style

This is new to Tahoe and only affects the rendering of icons and widgets. Liquid Glass settings don’t appear to have any effect on these.

Using light mode without any Accessibility changes, the Default setting for Icon & widget style is the baseline, showing icons in their ‘normal’ state.

Dark icon settings in light mode contrasts more but their readability may suffer.

When Icon & widget style is set to Clear, most are decolourised, making them significantly harder to read, and impossible to distinguish in the sidebar of System Settings.

The final option is for Icon & widget style to be Tinted (no relation to the Liquid Glass setting Tinted), where they’re rendered in monochrome using a colour of your choice, selected from the popup menu below. On iPhones and other devices that are available in several case colours, some have decided to set tinting to match the case, something you might like to try with an Apple silicon iMac, for example.

However, be careful in both Clear and Tinted styles, as it’s easy to end up making many icons unreadable and almost indistinguishable, here by setting the last of those to Graphite colour. This is one of the obvious drawbacks in Tahoe’s flexibility, in that many combinations of appearance mode, Accessibility settings and icon and widget style degrade its human interface rather than enhancing it. At least you now know what not to try, and how to return it to its defaults.

Summary of controls

• Appearance mode, Light or Dark, in Appearance settings;
• Liquid Glass, Clear or Tinted, in Appearance settings;
• Display variations to Reduce transparency or Increase contrast, in Accessibility settings, but those automatically override Liquid Glass settings;
• Icon & widget styles, in Appearance settings, with Icon, widget & folder colour when appropriate.

Apple has just released an update to XProtect for all versions of macOS, bringing it to version 5322. At the same time there’s an update to XProtect Remediator for Catalina and later, bringing that to version 156. As usual, it doesn’t release information about what security issues these updates might add or change.

This version of XProtect adds one new rule to its main Yara file, for MACOS.TIMELYTURTLE.DYCAOC, and amends the existing rule for MACOS.SOMA.OCENA. It also adds a new XPScripts.yr file containing two rules using an osascript (AppleScript) interpreter, MACOS.OSASCRIPT.COTABR and MACOS.OSASCRIPT.COTAWA.

XProtect Remediator 156, which follows version 153, adds one new scanning module, XProtectRemediatorConductor. It will be interesting to see whether this refers to a new codename, or its role among other scanning modules.

The XProtect Behavioural or Bastion rules embedded in XProtect Remediator 156 amend Rule 22, but don’t add any further rules.

You can check whether these updates have 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 these as a named updates in SilentKnight, their labels are XProtectPlistConfigData_10_15-5322 and XProtectPayloads_10_15-156

Sequoia and Tahoe systems only

This XProtect update has finally 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 5322 but your Mac still reports an older version is installed, you should be able to force the update using
sudo xprotect update

Update: the iCloud update was finally made available after 22:00 GMT on 5 November, over 24 hours after the release of this new version of XProtect.

Here are two reports on bugs affecting macOS Tahoe 26.1 that might make you wait before updating.

macOS VMs can’t access iCloud

If you update a macOS virtual machine to 26.1, or create a new VM in 26.1, it loses its Serial number, which is apparently set as 0. Although most things you might do with a VM aren’t affected by that, it will prevent that VM from being able to access iCloud (if that has been enabled for the VM) and related features.

There’s no workaround for this, as serial numbers are created when the VM is first made, and the user can’t add or change them after that. If your VM needs access to iCloud, keep it running 26.0.1 instead.

I’m very grateful to Rich Trouton of Der Flounder for this information, which is also given in Apple’s developer release notes.

Finder Services

In some Finder views, such as Column View, selecting an item at the left displays the item’s thumbnail and associated metadata. Below those are a selection of tools offering Finder services, such as Rotate Left, Markup, and more. Those are non-functional in 26.1, and if you want to use any of those services, you’ll have to use an alternative method, such as the contextual menu.

I’m very grateful to Michele for letting me know of this.

If you know of any serious bug that is new to 26.1, please let me know and I’ll add it to this list after confirmation.

Traditional oil paints were the mainstay medium used by professional painters in the west from the Renaissance until the late twentieth century, a period of well over half a millennium. Although other media have been used widely and successfully, until recently the apparently infinite flexibility of effects and painting styles made oil paint dominant. Over that period, much effort has been expended getting oil paint to dry more quickly, and discovering how to create stable paint layers using principles such as the ‘fat over lean’ rule.

In the nineteen-thirties Otto Röhm invented a new synthetic resin formed from acrylate molecules, dubbed acrylic resin. This first became available dispersed in liquid during that decade, and was steadily developed into paints during the nineteen-forties. Their biggest market was in commercial paints for general use, particularly for the outside of buildings.

In the late nineteen-forties, Leonard Bocour and Sam Golden developed and brought to market Magna paints, in which acrylates were suspended in mineral spirits to form an emulsion. Golden later developed a paint based on water, which lives on in his company Golden Artist Colours. In the nineteen-fifties they were joined by Liquitex, then in the sixties by Rowney’s Cryla paints. Acrylic paints were starting to rival oils.

In modern acrylic paints, the acrylics themselves are the binder, with water as its diluent. Wet paint is readily removed from brushes and skin using soapy water, making the use of organic solvents largely unnecessary except when dealing with dried paint. This is much more convenient than working with oils and their toxic organic solvents required for cleaning.

Oil paints remain rooted in alchemy to a degree; although modern commercially made oil paints are sophisticated combinations of natural and synthetic ingredients, using them and controlling their visual effects owes as much to tradition as it does to industrial chemistry. Acrylics are thoroughly modern in their formulation and use, carefully packaged blends of polymers with surfactants, plasticisers, dispersants, defoamers, stabilisers, and of course pigments.

Some artists still grind their own oil colours, and many oil painters use traditional media and resins to control their properties. Acrylics are too chemically complex for artists to prepare themselves, although use of special additive media to alter their handling and properties is popular.

Early acrylics were fast to dry, making them excellent for painting in layers, but unsuitable for techniques such as ‘wet in wet’ relying on the interaction of wet paint on the ground. Hard edges were easily achieved, as were bright if not garish colours, but effects such as sfumato were simply not possible.

Over the last fifty years, formulation of acrylic paints and their media have not only resulted in products that remain ‘open’ for longer, but have let painters determine body, flow, finish, and other physical properties of acrylic paint. Paint manufacturers even have fine control over the size of acrylic particles within the paint emulsion, enabling this flexibility, and some offer acrylic inks far more robust and durable than traditional products.

Acrylics are also able to adhere to a wide range of grounds. Professional artists often continue using prepared stretched canvas, but acrylic sizing is necessary on that and some others to prevent discolouration from the ground, termed ‘Support-Induced Discolouration’ or SID.

There are still remaining issues in using acrylic paints, though. Many oil paintings show evidence that at some stage part of their paint layer has been scraped off to enable the artist to repaint sections in pentimenti; this isn’t normally possible with acrylics, which tend to be overpainted without scraping, as the latter strips the entire paint layer and may also damage the ground.

Experience from accelerated ageing of acrylic paints suggests that today’s acrylic paintings should last better than oils. However, the oldest acrylic paints are still well under a hundred years old, making it far too soon to arrive at any definitive conclusion. It’s also telling that even the innovative Golden Artist Colours offers Williamsburg oil paints, and QOR watercolours using a synthetic replacement as its binder.

The update bringing macOS 26 Tahoe to version 26.1 is substantial, and has a great many increases in build numbers, so this overview of its changes concentrates on those substantial enough to merit an increment in version number. The update itself varies widely in size, ranging between about 3-14 GB, which is unusual and hard to explain.

Apple’s security release notes report that it addresses a total of 90 vulnerabilities, none of which have been reported as being exploited in the wild.

General release notes are extremely brief, and include:

• a new tinted appearance option for Liquid Glass,
• AutoMix support for Apple Music over AirPlay,
• better FaceTime audio over low bandwidth connections,
• Communication Safety and Web content filters are enabled by default for existing child accounts.

The only other release notes available are those for enterprise.

There are firmware updates to bring Intel T2 Macs to 2094.40.1.0.0 (iBridge 23.16.11072.0.0,0), and Apple silicon Macs to iBoot version 13822.41.1. The build number for macOS 26.1 is 25B78.

Version changes seen in bundled apps include:

• Audio MIDI Setup to 3.7
• Books to 8.1
• ColorSync Utility to 12.2.0
• Freeform to 4.1
• iPhone Mirroring to 1.5
• Music to 1.6.1
• News to 11.1
• Passwords to 2.1
• Safari to 26.1 (21622.2.11.11.9)
• Screen Sharing to 6.1
• Stocks to 8.1
• Tips to 26.1 (routine for this update)
• TV to 1.6.1.

Notable changes seen in /System/Library include:

• several PDF Automator actions have build increments
• Archive Utility has changed, with removal of a pref pane
• SystemIntents is a new app added to CoreServices at version 1.0
• two new driver extensions (dext) have been added, for AppleSunriseBluetooth and AppleSunriseWLAN
• kernel extensions updated include many for AGX, as well as AppleDiskImages2 and AppleEmbeddedAudio
• new kernel extensions include AppleSPINORFlasherDriver at version 1.0, and a family of AppleT8142 kexts to support the M5
• APFS is updated to version 2632.40.15
• added to DiagnosticExtensions are new items ScreenTimeDiagnosticExtension and ToolKitDiagnosticExtension
• added to PrivateFrameworks are new SpotlightDiagnostics and ThumbnailsBlastDoorSupport frameworks
• the RichText mdimporter is unchanged, remaining at version 6.9 (350).

As expected, the Spotlight bug described here recently remains unchanged in macOS 26.1.

One of the longstanding joys of the Mac has been how you can customise apps, giving them new icons and, in the past at least, even a few gentle tweaks. What’s unfortunate is that changing apps isn’t just for users. If we can alter them, so can an attacker, and the last thing any of us would want is for Safari or Preview to turn malicious. Over the years the scope for making changes to apps has therefore been reduced. This article explains how, and what we can still do.

To understand how customisation has been limited, we need to know what can and can’t change.

Signature

The most basic requirement of any app is that it’s signed. This provides a set of hashes that can be used to verify that none of its contents have been changed since that app was signed, and those hashes are hashed again to product code directory hashes, CDHashes, that are used to identify and recognise the app. Whatever we might customise in an app, its CDHashes must match its contents.

Certificate

Next comes the chain of trust established by the certificate used to sign the app. Developer certificates are issued by Apple as their Certificate Authority, so they each can be traced back through an Apple Intermediate certificate to Apple’s Root certificate, the chain of trust.

An Apple-issued certificate isn’t required for macOS to run an app, though. Because many Mac users build their own apps locally from open source, local or ad hoc certificates are also acceptable. However, anyone can sign an app with an ad hoc certificate, including an attacker, and, apart from the few malicious apps that have been signed using developer certificates, all other malware for the Mac is now ad hoc signed. As ad hoc signatures have no chain of trust, you can’t put any trust in them.

Notarization

Over the last few years, Apple has required developers to get their apps notarized. That involves ensuring the app meets certain security requirements, and is submitted to Apple to be checked to see if it contains any malicious code. Apps that satisfy those requirements are then issued with a ticket, that’s usually stapled inside the app’s bundle. That consists of the app’s set of CDHashes, again used to identify and recognise that app.

Although there’s no reason that you can’t notarize your own apps, and any you have resigned, that requires a paid-for subscription as a developer, putting it out of the reach of most. However, in an enterprise it can prove useful.

Launch constraints

Since macOS 13.3 Ventura, a new set of restrictions have been imposed on all apps and command tools provided as part of macOS, in launch constraints. These are rules that must be met for macOS to launch that app or binary, and include self constraints that the binary itself must meet, parent constraints that must be met by its parent process, and responsible constraints that must be met by the process requesting the launch.

Launch constraints for bundled apps prevent them from being run from anywhere else. If you manage to make a copy of any of those apps, and that’s a challenge in itself, then macOS will prevent you from running that copy. This is made harder to avoid by the fact that these launch constraints are stored in an inaccessible Trust Cache, so the only way you could work round those rules is by turning System Integrity Protection (SIP) off, which in turn reduces Boot Security. That’s explained in more detail here.

Although third-party apps don’t get to use launch constraints or the Trust Cache, some may now have started using environment constraints, which can have similarly restrictive effects. The best way to discover this is using Apparency, which also includes a full guide to the constraints available.

Bundled apps

If you can’t remember which apps are bundled and which are not, look in /System/Applications, as that shows all those in the Signed System Volume, to which you need to add Safari, as that’s sealed in a cryptex.

Sadly, because of all their levels of protection, you can’t customise any of the bundled apps. Even copying them from their read-only SIP-protected location to a folder in your Home folder, which is difficult enough, that copy can’t be run, no matter what you do to it. You can make a Finder alias to the original app and give that a custom icon that will appear in Finder windows. But the app’s original icon will still be displayed everywhere else, including in the Dock, so it’s simply not worth the effort.

If you had ideas that you could replace all Tahoe’s new-style app icons with those from Sequoia, I’m afraid you will be disappointed.

Third-party apps

One customisation you can apply in complete safety is to replace a regular app’s icon. To do that, paste the new icon into the top left of its Get Info dialog, and further information is given here. This doesn’t affect any of the security protection of that app, as the new icon is added as a hidden Icon file at the top level inside the app’s bundle, which isn’t included in its CDHashes.

Any more substantial changes, even to the app’s resources, should break its signature and CDHashes, and macOS won’t like that.

If there’s a really good reason for making a change, and you can justify resigning the app using an insecure ad hoc signature, you could try stripping its current signature, changing the app bundle, then resigning it with an ad hoc signature. There are two cautions, though:

• Any ad hoc signature is inherently insecure, and makes it simple for malicious code to tamper with that app.
• This may break the app’s updating process, and if it doesn’t, any update will undo your customisation.

Before going any further, you’ll need to add Terminal to the list in System Settings > Privacy & Security > App Management, otherwise your commands will be unable to make any changes to the app. Then make a copy of the app you intend to change, so you can readily revert to the original. Once you’ve done that, open Terminal and use the command
codesign --remove-signature MyApp.app
to strip the existing signature from the app MyApp.app. Note that two hyphens precede the remove-signature verb.
When you’ve made your changes, use the command
codesign --sign - MyApp.app
to sign that app with an ad hoc signature.

Summary

• Apps bundled in macOS from 13.3 onwards can’t be copied and run from elsewhere, preventing all customisation, and can’t be given custom icons.
• Third-party apps can have custom icons applied in the normal way.
• Any internal surgery inside the app bundle will break its notarization and signature, and shouldn’t be attempted.
• If it’s an essential change, you may be able to strip the signature, make the change, and resign with an ad hoc signature.
• Ad hoc signatures are inherently insecure, and should be avoided if at all possible.

Apple has just released macOS 26.1 Tahoe, together with security updates for Sequoia to bring it to 15.7.2, and for Sonoma to 14.8.2. There are also separate updates for Safari in 15.7.2 and 14.8.2.

The Tahoe update has at last appeared here in Europe, and is a hefty 4.7 GB for Apple silicon Macs.

Security release notes for 26.1 report around 90 vulnerabilities have been fixed, none of which have been reported as being exploited in the wild. Listings for Sequoia give about 54, and for Sonoma about 46.

The only other release notes available so far are for enterprise here.

Details provided by Apple beyond the general ‘bug fixes and updates’ include a new tinted option for Liquid Glass, that has already been widely discussed among beta-testers, Apple Music AutoMix support over AirPlay, better FaceTime audio in low bandwidth connections, and Communication Safety and Web content filters enabled by default for existing child accounts. That seems surprisingly little to squeeze into a mere 4.7 GB, and I suspect there will have been more extensive changes.

The build number for macOS 26.1 is 25B78. Firmware in Apple silicon Macs is updated to iBoot version 13822.41.1, and Safari is version 26.1 (21622.2.11.11.9).

I will post a detailed analysis of changes tomorrow, 4 November.

Important note for those intending to update to 15.7.2 or 14.8.2 rather than Tahoe:
To be certain the correct updates will be installed, in the Also Available section of Software Update, click on the ⓘ button to the right of the Update Now button for Other Updates and select the appropriate macOS update and Safari, deselecting the Tahoe update there. That should ensure you don’t inadvertently upgrade to Tahoe.

[Last updated 06:42 4 November 2025]

Dante and Virgil move on from their encounter with Count Ugolino towards a great contraption that looks like a windmill from the distance. As they grow closer, they pass by shades of the dead frozen and stacked up.

Virgil then shows Dante the ruler of Hell, a huge giant frozen up to his chest. He has three faces: one looking forward is bright red, that on the right a dirty yellow, and on the left black. Behind each face is a pair of vane-like wings fanning the ice-cold wind blowing across Lake Cocytus.

His six eyes are weeping, and each mouth is chewing one of the souls from that pit of Hell. Virgil points out that one of them, his legs protruding from Lucifer’s lips, is Judas Iscariot, who betrayed Jesus Christ for thirty pieces of silver. The other two are Brutus and Cassius being punished for their assassination of Julius Caesar.

Virgil tells Dante that he has now seen the whole of Hell, and it’s time for them to leave. They make their way up some steps through a fissure in the rock.

Where Dante expects to see the body of Lucifer again, he sees just his legs.

Virgil tells him they must move on quickly, now the sun is rising. They walk through a cavern, along a path long and arduous. Eventually they emerge below the stars. With that, Dante’s account of his visit to Hell is complete.

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, first published in 1857 and still being used. These were followed in 1867 by more illustrations for Purgatorio and Paradiso. This article looks at his paintings.

John Flaxman (1755–1826) was a British sculptor and draughtsman who occasionally painted too. When he was in Rome between 1787-91, he produced drawings for book illustrations, including a set of 111 for an edition of The Divine Comedy. In 1810, he was appointed the Professor of Sculpture to the Royal Academy in London, and in 1817 made drawings to illustrate Hesiod, which were engraved by William Blake.

Joseph Anton Koch (1768-1839) was an Austrian landscape painter, who worked mainly in Neoclassical style. During his second stay in Rome, he was commissioned to paint frescos in the Villa Massimi on the walls of the Dante Room there, which remain one of the most florid visual accounts of Dante’s Inferno. He completed those between 1824-29. He also appears to have drawn a set of illustrations for Dante’s Inferno in about 1808.

Filippo Napoletano (1589–1629), whose real name was Filippo Teodoro di Liagno, was an Italian painter who worked in Naples, Florence and Rome, mainly painting dramatic landscapes. He was a court painter to the Medicis from around 1617, who also painted a nocturne of the burning of Troy.

Wilhelm Trübner (1851–1917) was a successful realist painter who was born in Heidelberg and worked almost entirely in Germany. In 1872, with Hans Thoma and others he formed a circle who admired the work of Wilhelm Leibl (1844-1900). His peak is claimed to have occurred in the mid-1870s, and in 1901 he joined the Berlin Secession. During his later years he was a professor in Karlsruhe.

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 332. Here are my solutions to them.

1: I came in 1998, Bondi blue with USB.

2: I came a year later, with a PowerBook ID and AirPort.

3: I came two more years later, with the smallest hard disk and LCD, and a thousand songs.

The common factor

I look forward to your putting alternative cases.

For good practical reasons, provided an app was signed using a certificate that was valid when the developer signed it, that certificate remains valid in perpetuity unless Apple (as the Certificate Authority) revokes it. But signatures in installers, including those for macOS and its components, must be valid when you run that installer. When any of the certificates used in Apple’s installers expire, Apple has to release a new installer with a certificate that remains valid into the future.

Six years ago, on 24 October 2019, Apple’s intermediate security certificate it had been using to sign all macOS installers and updaters expired. That also applied to most if not all Apple’s user signing certificates, but not the Apple Root CA. The consequence is that none of the installers provided with certificates expiring in 2019 will work on Macs running with a more recent date.

To check whether an installer is affected, double-click it to open it in the Installer app. At the top righthand corner of its window is a small padlock: click on that to review its certificate information. Most Apple installers refer to three levels of certificate:

1. Apple Root CA, the root certificate authority, should expire in 2035.
2. Apple Software Update Certification Authority provides the intermediate certificate, which may have expired on 24 October 2019.
3. Software Update, the user certificate, may also have expired on 24 October 2019.

Normally it’s number 2 above that is the most critical: once an intermediate certificate has expired, all chained user certificates become invalid. Currently, the intermediate certificate for all third-party developer certificates doesn’t expire until 2027. It’s unclear why Apple gives its own certificates an intermediate that expires after less than five years, and you might recall the previous time this happened was in February 2015.

If you have an old Mac and want to install or update macOS on it, using an old installer package with expired certificates will fail. To work around that, you’ll need to locate an installer with updated certificates that remain valid on the date that you perform that installation. There are several ways to accomplish that, with an excellent compilation given by Mr. Macintosh.

One popular way of working around this is to deliberately set your Mac’s clock back to a date before those certificates expired, such as 20 October 2019. Although that’s easy to do, it has far-reaching consequences that you should consider before trying it.

A great deal of macOS depends on the accuracy of date and time stamps. For example, it’s a general rule that the creation timestamp of a file or directory should be the same as or earlier than its modification and other timestamps. Some software used to make backups may become confused with file creation times that are not only more recent than their modification timestamp, but are also more recent than the current clock time. This can also feed through into the FSEvents database used by Time Machine to determine what it should back up, and more.

Macs suddenly running at some time in the past create difficulties in the log as well. You may well discover that log entries written at times set to be days or years ago can’t be found, particularly if you do later return that Mac to correct time. That’s another decision you need to think through carefully: once you have run the outdated installer, will you return the clock to normal timekeeping, so it leaps forward by more than 6 years?

As a general principle, don’t try fiddling with your Mac’s clock to pretend it’s a time in the past. That may leave you a mess that is too deep-seated to be put right.

In the first of these two articles showing paintings of Spartans from the city-state in ancient Greece, I illustrated some of the laws laid down by the founder of its warrior tradition, Lycurgus.

When those laws were all in place and in practice, Lycurgus told an assembly of all Spartans that he needed to return to the oracle at Delphi to consult on one final measure. He made the Spartans take an oath to abide by these unwritten laws until his return, then departed for Delphi. There he obtained the approval of the oracle, which he recorded in writing and sent back to Sparta.

This undated painting of Lycurgus Gives the Laws to the Spartans has been attributed to either Jacopo Palma il Vecchio (c 1480-1528) or Bonifazio Veronese (1487-1553). It shows an elderly Lycurgus apparently giving a volume of written law to the Spartans in the marketplace, but could equally be of Lycurgus addressing his last assembly of all Spartans before he left for his second visit to Delphi.

Merry-Joseph Blondel’s portrait of Lycurgus of Sparta from 1828 also shows him as an older man, here with written scrolls on his right thigh. Given the oral nature of Lycurgus’ laws, this can only be interpreted as the moment that Lycurgus has written his message reporting the oracle’s approval of his laws, ready to send it back to the city.

Lycurgus then did something extraordinary in its selfless ingenuity: having put the whole of Sparta under oath to keep his laws until his return, he then starved himself to death, ensuring that oath could never expire. The laws of Lycurgus lasted through fourteen kings, and five hundred years, without change, until gold and other spoils of war entered Sparta during the reign of King Agis.

The single most celebrated event in Spartan history is the Battle of Thermopylae in 480 BCE, in which three hundred Spartan soldiers, with 700 Thespians and 400 Thebans, were claimed to have kept over one hundred thousand Persians at bay for three days. This is the more remarkable for the fact that the Spartans and their supporters fought to the death, following which the Persians overran Boeotia and captured Athens. It is thus an example of self-sacrifice in the face of overwhelming odds, resulting in most noble defeat.

The only major painting that I have been able to discover of this is Jacques-Louis David’s Leonidas at Thermopylae (1814). Leonidas, the Spartan King and commander of the force, is at the exact centre of the painting, the viewer fixed in his emotionless gaze. Around him are his three hundred Spartan warriors, with supporting trumpeters, a lyre hanging on the tree, and laurel crowns being handed round.

David leaves some clues to his narrative in inscriptions, which have unfortunately become barely legible. A soldier has climbed up to carve an inscription in Greek at the upper left, the word HERAKLEOS appears on a plinth to the left of Leonidas, and by his right foot is an anachronistic piece of paper bearing more Greek words.

More subtle, perhaps, are the small groups driving pack animals along a narrow path at the upper right: the Persians were shown a mountain path around the narrow pass at Thermopylae, enabling them to gain an advantage over the Spartans.

Recent artistic interest in Thermopylae seems to have started around 1960, and first reached popular culture in Rudolph Maté’s 1962 movie, The 300 Spartans, which has been interpreted as comment on the Cold War at the time. This in turn inspired Frank Miller’s graphic novel 300, which was first published in 1998, and made into a highly successful movie of the same name by Zack Snyder, released in 2006.

In contrast, Sparta’s three wars against the state of Messenia are little-known. Gustave Moreau’s fascination for esoteric ancient history led him to start painting a scene from the Second Messenian War in about 660-650 BCE.

Moreau seems to have worked on Tyrtaeus Singing During the Combat in the early 1860s, abandoned it, then returned to have it enlarged in about 1883, and work it further for a period, before finally giving it up altogether.

This detail shows much of his original painting, which is full to bursting with androgynous and near-naked young men. The priestess-like figure to the left of the centre appears to be Tyrtaeus, an elegiac Greek poet whose verse exhorted the Spartans to fight bravely against the Messenians. He is shown here in action, inspiring the young Spartan warriors to victory. The strange collage-like effect is a combination of Moreau’s emphasis on establishing the form of his figures, and I suspect edge-enhancement in the image’s processing.

Spartans also played a central role in the war with Troy, the result of Paris’s abduction of Helen, a Spartan woman whose origins are the subject of dispute. Later Roman accounts, the basis of most more recent paintings, claim she was the outcome of the union of Leda, wife of Tyndareus, King of Sparta, with Zeus, in the form of a swan. Those dating back to the time of the Cypria and the Epic Cycle are more complex, and make Helen’s mother Nemesis, the personification of public disapproval.

In the Greek version, Zeus appeared to Leda as a swan. Both he and Tyndareus impregnated Leda at about the same time, but as Zeus was then in the form of a swan, her twin pregnancies resulted in two eggs: one hatched into Castor, who was human because his father was Tyndareus; the other hatched into Polydeuces (Latin Pollux), who was divine as his father was Zeus. Despite their different fathers, the twins were known as the Dioskuroi, who were later to rescue Helen.

This interpreted copy of Leonardo da Vinci’s Leda and the Swan, probably painted in the early 1500s and now in the Philadelphia Museum of Art, summarises the later account of Helen’s unique birth, with two eggs and a fourth baby, Clytemnestra. Later paintings, perhaps wisely, concentrated on Leda and Zeus, and skipped the incredible egg phase altogether.

According to most accounts, when Helen was still under age, she was abducted by Theseus, the ‘hero’ who abandoned Ariadne on the island of Naxos. Helen’s adopted brothers the Dioskuroi were unimpressed by this, so they paid Theseus a visit, and persuaded him to return their step-sister. In return for her son’s offence, Aethra, mother of Theseus, was made Helen’s slave, and wasn’t freed until after the fall of Troy many years later.

Jean-Bruno Gassies’ painting of Castor and Pollux Rescuing Helen was runner-up in the Prix de Rome in 1817. The woman being escorted away at the left may have been intended to be Theseus’ mother Aethra, although she appears remarkably young.

Helen’s beauty only grew over time, and her hand was sought by many suitors in a contest organised by her brothers Castor and Polydeuces. Among those suitors were many prominent figures, including Odysseus. Helen’s father, King Tyndareus, feared that in choosing between her suitors he would offend and cause trouble. The suitors therefore agreed to swear an oath, under which they would all defend the successful suitor in the event that anyone should quarrel with them, the crucial Oath of Tyndareus. Under that, Menelaos, King of Sparta, was chosen as Helen’s husband.

Helen was the bribe offered by Aphrodite to Paris for judging her the winner of the golden apple of discord. For nine days, Helen’s husband Menelaos entertained Paris as a guest, while Paris plied her with gifts. On the tenth day, Menelaos was called away to Crete for his grandfather’s funeral. He left his house in Helen’s charge, reminding her to ensure their guests were well cared-for, although clearly not in the way that Paris was intending.

For Tintoretto, The Rape of Helen (1580) was nothing short of war. As an archer is about to shoot his arrow, and another Trojan fends off attackers with a pike, Helen, dressed in her finery, is manhandled onto Paris’s ship like a stolen statue.

Thus the Spartans were at the centre of the Trojan War.

Having waded through dozens of CPU core frequencies for all current members of the M-series families of chips, you might be wondering what they mean for someone considering buying a new Mac. Is the M5 going to prove any faster than an M4, or should they wait until M5 Pro or Max variants become available?

All else being equal, a core that runs at a higher frequency should process instructions more quickly than a similar core running at a lower frequency. But these figures only apply to the CPU cores, and much of their most demanding code is now run on other co-processors and components, including the GPU and neural engine (ANE).

The M5 has specific enhancements to its GPU to accelerate its performance when running compute tasks that can be common in AI and other advanced code. That GPU runs Metal code, and because that’s compiled and prepared by the CPU cores, to obtain maximum performance from its enhanced GPU the CPU cores also need to perform well. CPU cores play other key roles in supporting specialist components, so matching their performance is essential to avoid bottlenecks and achieve balance. One consistently important factor is the speed of memory access: the faster everything goes, the faster data has to be moved around, and that’s why minimising movement using Unified Memory can prove so important, as is the M5’s faster bandwidth of 153 GB/s, compared with 120 GB/s in the base M4.

There’s also more to CPU core performance than just frequencies. Cores can execute instructions out of order, predict load addresses and values, and pull other tricks to ensure that best use is made of every clock cycle. For the M5, Apple has singled out claimed improvements in multithreaded performance, enabling a single core to run multiple threads significantly faster.

Looking just at CPU cores, the table above compares all the M-series chips released to date, ignoring ‘binned’ and other cut-price sub-variants. Columns labelled Σfn are a crude indicator of performance capacity for the whole CPU, obtained by totalling numbers of cores multiplied by their frequency,
(P x fP) + (E x fE)
where P and E are the numbers of P and E cores, and fP and fE are their respective maximum frequencies. It’s here worth mentioning what a monster the M3 Ultra is in comparison to any other M-series chip.

Because M5 core frequencies don’t currently include Pro or Max variants, those given are starting points. I’d expect to see P cores in the M5 Pro and Max variants reach a maximum frequency of at least 4.7 GHz, although their E cores may be restricted to a lower maximum than the 3.05 GHz of the base variant, to ensure they achieve good economy, as for the M4.

Base variants in Apple’s M-series chips have the fewest P cores in each family, only 4, typically half the number of their Pro variant. Although those should be ample for much of the time, when there are too many high priority (Quality of Service) threads running for user apps, some may overflow to be run on the E cores instead. This is where those frequency tables come into play, as those E cores will be run at higher frequencies to compensate. As the maximum frequency of the E cores in an M5 (3048 MHz) is significantly higher than that of a base M4 (2892 MHz), the base M5 should run those overflowed threads faster.

Another important aspect of the M5 that isn’t clear yet is which version of the Arm Instruction Set Architecture (ISA) it supports. The M4 surprised us with its support of the Armv9.2A ISA, and this year’s A19 and M5 chips are believed to support 9.4A or possibly 8.7. This is particularly relevant to security, as either of those should bring support for Arm’s Enhanced Memory Tagging Extension, which is required to support Apple’s new Memory Integrity Enforcement (MIE), already announced for the A19. Early reports are that the M5 does indeed support the required ISA and its extension, ready for the implementation of MIE in the coming months, if it’s not already built into macOS 26 Tahoe.

Like much else in the base M5 chip, frequencies and features are largely evolutionary, but its enhanced support for GPU compute, faster memory and improved multithreaded performance should deliver substantial improvements. If it’s also the first Mac chip to support Apple’s new security feature MIE, the base M4 is outclassed.

For all the untold number of paintings of classical myths, there are but a tiny number of works that strive to show historical events and scenes in the great classical civilisations. Even fewer of those show the most anomalous of the classical cultures, that of Sparta. Yet in recent years interest in Sparta, the Spartans, and their extreme way of life has risen, and is reflected in a wealth of modern imagery in graphic novels, movies, and computer games.

This weekend I look at some of the more significant paintings made of the Spartans prior to 1900.

Sparta was the capital of a city-state in ancient Greece, founded as a monarchy in about 930 BCE. The founder of its renowned warrior tradition was Lycurgus, who lived some time between 900-800 BCE and laid down much of the law and institutions of the Spartan state, although he refused to be its king.

Before Lycurgus implemented his reforms, he visited the Oracle at Delphi, who told him that the state which observed his laws would become the most famous in the world. Pythia, the high priestess at Delphi, is shown in Eugène Delacroix’s Lycurgus Consulting the Pythia (1835-45) listening intently to Lycurgus, before giving her prophesy.

Lycurgus was born into a Spartan family, and it’s most probable that he was the son of a reigning king of Sparta who lost his life when he was stabbed with a butcher’s knife as he intervened in a riot. Lycurgus’ older brother Polydectes inherited the throne, but died shortly afterwards.

Polydectes’ wife was pregnant at the time, so Lycurgus could only reign until that child was born: if a boy, then the child would succeed to the throne. After eight months of Lycurgus’ rule, a son Charilaüs was born, and Lycurgus proclaimed him king. To allay suspicion that he might try to usurp the authority of the new king, Lycurgus left Sparta and travelled. This gave him the opportunity to visit other kingdoms to learn of the strengths and weaknesses of the laws and institutions of Crete, the Ionians, and Egypt.

Lycurgus resolved to revolutionise Spartan society by introducing a completely new regime. He therefore visited the oracle at Delphi to discover whether his ideas were sound. The high priestess addressed Lycurgus as “beloved of the gods, and rather god than man”, and endorsed his proposals, that she said would be the best in the world.

His next task was to win over the senior Spartans, so they would be happy to implement his laws. Once he had convinced many of them, Lycurgus got thirty of them to go into the marketplace at dawn, and with their weapons to strike terror into those who opposed the proposals. King Charilaüs first fled to a refuge, then returned to give Lycurgus his support.

The changes made to Spartan law, institutions, and society were fundamental and extensive. Lycurgus established a Council of Elders with twenty-eight senators, to ensure that no king could become a tyrant, and the state couldn’t drift towards democracy. Land was redistributed uniformly and equally in lots: 30,000 in the surrounding countryside of Laconia, and 9,000 in the city of Sparta.

Lycurgus withdrew all gold and silver coinage, leaving only iron in circulation. He then devalued that currency, so that being rich in it would require a large store-room full of heavy iron coins. This forced equality in terms of money and possessions, and helped banish superfluous arts and trades, killing all luxury. To ensure a communal life for the good of society as a whole, he introduced common messing, so that Spartans all ate in large groups, on a simple but healthy diet.

Wealthy Spartans grew incensed with these changes, and started to stone Lycurgus, who was forced to flee from the marketplace. One young Spartan, Alcander, managed to blind him in one eye before he reached safety. Rather than have Alcander put to death, Lycurgus took him in as a servant and companion, so the young man became his most devoted follower, and convinced other opponents to support the reforms.

In his Lives, Plutarch provides considerable detail of the diet provided by these common messes, the fact that Spartan boys attended them, and there learned to withstand others jesting at them.

Lycurgus didn’t put these laws into writing, but established an educational system to instil them into future generations. Other unwritten laws included the requirement for all laws to remain unwritten, and the avoidance of extravagance in property, by the use of common building materials and standards.

The narrative in Caesar van Everdingen’s Lycurgus Demonstrates the Benefits of Education from 1660-62 doesn’t appear to relate directly to Plutarch’s text, but shows a young Lycurgus with a couple of young Spartan men, their hair cropped short.

The new laws also regulated marriages and births. As Spartan men were away on military expeditions much of the time, Lycurgus gave their wives sole control when their husbands were away, and the title of Mistress. He ensured that unmarried Spartan women kept healthy, by prescribing that they too undertook running, wrestling, throwing the discus, and the javelin.

Spartan society appears to have been distinctive, perhaps unique, among the many small states of ancient Greece for its dedication to a single product: the perfect (male) warrior. From cradle to grave, males were reared, educated, trained, and worked for the single task of fighting the state’s enemies.

Because Spartan women had the crucial role of producing infant warriors, and of keeping the state going while their menfolk were away for long periods training and fighting, they were highly valued in those roles. They were even encouraged to acquire supporting skills, that enabled two Spartan women to become victors in the Ancient Olympic Games. Lycurgus urged young Spartan girls to engage in wrestling, presumably so that they could defend the homeland when their menfolk were absent.

The process of turning a male baby into an adult warrior is known as agoge, and is detailed in this fascinating Wikipedia article.

Christoffer Wilhelm Eckersberg’s Three Spartan Boys Practising Archery (1812) shows three young boys progressing through their training in basic military skills.

Once old enough and sufficiently skilled, a young man would be given his shield by his mother, as shown in Jean-Jacques-François Le Barbier’s A Spartan Woman Giving a Shield to Her Son. The mother’s instructions would have been for her son to return either with his shield, or on it: he had to make a success of his training, or to die trying.

Education in Sparta (1850) was, I believe, painted by Cesare Mussini, or possibly his brother, and shows some of the less attractive aspects of the agoge, as one young man has clearly been overdoing the drink. There are also subtle allusions to the acceptance if not encouragement of pederastic relationships.

If this work is by Mussini, the quality of its paint layer should be superb, as Mussini used his own resin-based formulation for oil paints. These were so successful that he was able to sell the recipe to H Schmincke, whose company has continued to sell oil paints based on Mussini’s formulation ever since.

By far the most famous depiction of Spartans is a second attempt by Edgar Degas, Young Spartans Exercising from about 1860, now in the National Gallery in London.

Degas’ first attempt, Young Spartan Girls Challenging Boys (c 1860), shown above, was abandoned, but gives insight into the second.

Four Spartan girls taunt six Spartan boys in front of a substantial building. Around that building is a group of Spartan women, presumably mothers of the boys and girls in the foreground, who are talking with Lycurgus. Behind that building is the city of Sparta, and in the distance to the left, behind the girls, is Mount Taygetus, where unfit Spartan babies were abandoned to see if they survived and merited life. Degas may at this stage have wanted to make the visual association between the girls, who would in due course become mothers, and the mountain where some of their infants would have to be abandoned.

Young Spartans Exercising (1860) appears to be an oil study for his second version of this painting, adopting Degas’ revised composition.

Young Spartans Exercising (c 1860) was Degas’ most complete second version, which he listed for display at the Fifth Impressionist Exhibition in 1880, but doesn’t appear to have been shown there.

One of the boys, whose head is just visible in the first version, has been removed, but the two groups otherwise remain similar to the first version. The building in the middle distance has been removed to open the view out, and as a result the group of mothers with Lycurgus appears less prominent and more distant. The whole image has been stretched along its horizontal axis, moving Mount Taygetus to the left of the group of girls.

Degas had undoubtedly read Plutarch’s life of Lycurgus, including the passage:
He freed them from softness and delicacy and all effeminacy by accustoming the maidens no less than the youths to wear tunics only in processions, and at certain festivals to dance and sing when the young men were present as spectators. There they sometimes even mocked and railed good-naturedly at any youth who had misbehaved himself; and again they would sing the praises of those who had shown themselves worthy, and so inspire the young men with great ambition and ardour. For he who was thus extolled for his valour and held in honour among the maidens, went away exalted by their praises; while the sting of their playful raillery was no less sharp than that of serious admonitions, especially as the kings and senators, together with the rest of the citizens, were all present at the spectacle.

Degas continued to work sporadically on this painting, leaving it unfinished when he died. The artist never explained his intention, nor did he provide any clues as to how this painting should be read. Modern readings characteristically concentrate on gender contrasts and conflict, but all too often ignore its background, both visually and in historical context.

Marriages became open, in allowing both husband and wife to have relations with the partners of others. Sons were considered not to be ‘owned’ by their fathers, but by the state itself. Newborn infants were taken to a place called Lesche, where they were examined by elders, who decided whether the child was healthy and sturdy. If it was, it was assigned one of the 9,000 plots of land, and reared by its parents. Babies deemed frail or ill-formed were abandoned at Apothetae, a chasm at the foot of Mount Taygetus, to die.

The examination by elders at Lesche is the subject of two little-known paintings that appear to have a common origin. The first, claimed to be by Jacques-Louis David and titled Lycurgus of Sparta (1791), shows this process taking place, with a queue of young parents. A newly-born infant is being presented to the elders for their verdict, perhaps with Lycurgus acting as the organiser.

This painting by Jean-Jacques-François Le Barbier is titled The Magnanimity of Lycurgus and was apparently made in the same year of 1791. All its key elements correspond to those in the David, as if one artist partly copied the other.

Plutarch provides lengthy details of the rearing and education of Spartan children, and the effects on Spartan culture. These he summarises thus:
[Lycurgus] trained his fellow-citizens to have neither the wish nor the ability to live for themselves; but like bees they were to make themselves always integral parts of the whole community, clustering together about their leader, almost beside themselves with enthusiasm and noble ambition, and to belong wholly to their country.

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

1: I came in 1998, Bondi blue with USB.

2: I came a year later, with a PowerBook ID and AirPort.

3: I came two more years later, with the smallest hard disk and LCD, and a thousand songs.

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.

When you run a command tool you invoke its options in the command you enter. Those options are supplied each time you run the tool, and don’t persist. Apps are different, in having a GUI that usually offers the user options, and in relying on information that persists until you next run that app. Those are its preferences, settings or defaults, depending on how you look at them.

In traditional Unix, persistent preferences may be implemented as configurations, defined in a plain text config file. In classic Mac OS window settings and a great deal more were saved as resources, in the resource fork of the app or its documents. This resulted in one neat feature that’s seldom seen in macOS today, saving a document’s window settings to its file, so they will be reused the next time that document is opened.

One of the innovations in NeXTSTEP was the human-readable property list used to store serialised objects such as preferences. These consist of designated variables used by the app that are converted into a representation that can be expressed in text. For example, if an app lets the user decide whether to use US or metric units of measurement, that could be stored in memory as a Boolean variable, true or false, and serialised as the word true or false in a property list used to store the app’s preferences.

Contents

Accommodating all the preferences needed by an app usually requires a dictionary of those serialised values, each given a key for identification, and having an explicit or implicit data type. Thus, that user option might become
key: metricUnits
value: true, a Boolean with two possible values.

Mac OS X replaced the old NeXTSTEP format for property lists with two formatting schemes, XML and JSON, with XML the standard for app preferences. This is a file containing dictionaries of key-value pairs representing the serialised data:
<dict>
<key>metricUnits</key>
<true/>
<key>filePrefix</key>
<string>MyFile</string>
</dict>

Initially, all property lists were stored as plain text, but that’s woefully inefficient, so between Mac OS X 10.2 and 10.4 a more compact binary format replaced that, and remains the standard today, as implemented in the UserDefaults API.

cfprefsd

Although developers can handle their app’s defaults/preferences with their own code if they wish, macOS provides the defaults server cfprefsd, and that convenient API that is used by the great majority of apps. Under that, early in an app’s initialisation cfprefsd automatically opens that app’s preferences, then loads its key-value pairs to make them available to the app as it’s setting itself up.

cfprefsd is transparent to the developer, whose code simply accesses key-value pairs as they are required. cfprefsd may opt to keep the whole preference file in memory, and manage it however it sees fit. Thus the property list’s contents on disk may not represent those held in memory for the app, and any changes to the property list file may be overwritten when cfprefsd saves changed values from memory.

For a simple app, working with cfprefsd should also be straightforward. The app’s preference property list is opened by cfprefsd shortly after the app is launched, and the app’s code works through UserDefaults to make any changes to key-value pairs while the app is running. As the app is shut down, cfprefsd updates the preference file, and the user is once again free to change or delete that property list as they wish. However, there’s ample scope for that to become more complicated, or to misuse it.

Problems

Many apps today aren’t that simple in their structure, and use helper apps and other executable code that may still be running with access to the app’s preferences even though the main app is shut down. When the user thinks it’s safe to modify the contents of that property list, it may still be in the care of cfprefsd. The preferred approach then is to use the defaults command tool, which should work with cfprefsd rather than competing with it.

In the past, UserDefaults and cfprefsd weren’t always reliable, and some developers worked around their problems with a combination of the official API and performing their own direct manipulation of preference files. Those dangerous practices should have died out now.

Because an app’s preferences are accessed early as it’s being launched, any bugs or incompatibilities in those key-value pairs can have fatal effects before the app is fully open. For example, if a new version of an app reuses an existing preference key with a different data type, if it reads an old version of its preferences, that will throw an error. If that’s not handled well, that can cause the new version of the app to crash when launched.

Fortunately, all apps have to be able to create their own preference file for when they’re first run. There’s scope for further bugs there, when the file created isn’t updated to work with changed key-value pairs in a newer version of the app. That may result in an app that crashes when launched even when there’s no existing preference file saved, a problem for which there’s no workaround.

Finally, many apps have multiple preference files. If they run in a sandbox, the copy they use normally is in the Data/Library/Preferences folder in their container, in ~/Library/Containers. But they may also have a different property list in ~/Library/Preferences, and sometimes a master copy in /Library/Preferences as well. While I’m sure cfprefsd knows which to access, you may need to check by inspecting each file’s timestamps.

UserDefaults have improved significantly with SwiftUI, further integrating persistent storage of preferences. Although they can still trip up the unwary, provided you understand how they work and don’t try fighting the system, they should seldom cause substantial problems.

Further reading

UserDefaults (Apple)
Preferences and Settings Programming Guide (Apple) from 2013
Thomas Tempelmann’s Prefs Editor works with cfprefsd

With the outbreak of the Franco-Prussian War in 1870, Gustave Doré volunteered to serve in the National Guard. When he was trapped in the siege of Paris, he seized the opportunity to paint his friend the actress Sarah Bernhardt (1844-1923), in what was probably the first portrait in her long and glittering career.

She was only twenty-six at the time, and was just starting a string of successful performances in the city’s Odéon theatre. During the siege she took charge of converting the theatre into a hospital that cared for more than 150 patients. When it re-opened as a theatre the following year, Bernhardt took the lead for a highly successful run. On its opening night, Victor Hugo, author of the play, knelt and kissed her hand.

Doré also produced a series of moving sketches showing the destruction and suffering in Paris at the time of its siege in the autumn of that year.

Among those is his Sister of Charity Saving a Child. An Episode of the Siege of Paris (1870-71).

The following year he committed some of his apocalyptic visions of the siege to canvas, in The Enigma (souvenirs de 1870), and two other major paintings. All three were made using grisaille, greys normally used to model tones in traditional layered technique.

This shows the shattered and still-burning remains of the city in the background, bodies of some of the Prussian artillery in the foreground, and two mythical beasts silhouetted in an embrace. The winged creature is female, and probably represents France, who clasps the head of a sphinx, who personifies the forces that determine victory or defeat. The enigmatic question would then relate to the Franco-Prussian War, and the reasons for France’s defeat.

When Doré visited London he was shocked by its large population of vagrants and homeless. This print of A Couple and Two Children Sleeping on a London Bridge (1871) is one of several records he made at the time, from which a selection was included in his illustrated book on London published the following year.

Doré continued to paint religious narrative works, in particular several versions of Christ’s Entry into Jerusalem. This, a preparatory sketch for his final huge version exhibited at the Salon in 1876, shows his brushwork at its loosest and most gestural. This shows the conventional Christian account in the Gospels, of Christ entering Jerusalem in triumph on the back of a donkey, as the start (‘Palm Sunday’ because of the palm fronds usually involved) of the series of processes leading to his Crucifixion. A popular biblical narrative in European painting, few finished works can match Doré’s at 6 by 10 metres (20 by 33 feet).

In 1873 he visited the Scottish Highlands to fish for salmon, and fell in love with the country. Two of his best paintings of the Highlands are Scottish Highlands (1875) above, and Landscape in Scotland (c 1878) below. These were painted in his studio from the sketches and studies he had made during his tour.

Doré also had good business reasons for being in Britain: in 1867, he held a major exhibition of his work in London, leading to the opening of his Doré Gallery in Bond Street, London. He additionally completed a five year contract with a publisher that required him to stay in London for three months each year.

At the time of his death in 1883, Doré was close to completing another huge painting showing The Vale of Tears. Drawn not from the Gospels but instead from Psalm 83, reinforced in the writings of Saints Jerome and Boniface, and in the mediaeval hymn Salve Regina (‘Hail Holy Queen’), it refers to the tribulations of worldly life left behind when the pious enter heaven. It’s sometimes known as the Valley of Tears.

Christ, bearing a full-sized cross, is in the distance, surrounded by an arch of light. He is beckoning a large crowd struggling up a steep and rough track leading towards him, and the rocky mountains behind. People in the crowd are of all ages, from infants to the aged, many with obvious physical disorders and ailments, all apparently suffering in their ascent up the Vale of Tears. I wonder whether Doré knew that his journey was also coming to a close.

Gustave Doré died in Paris on 23 January 1883 at the age of only 51. His illustrations live on today even though his paintings may have been sadly forgotten.

By international disagreement, last Sunday morning the UK, along with Europe, set its clocks back an hour from British Summer Time to good old GMT, and this coming Sunday it’s the turn of most of the US to do the same. Unless you’re in Hawaii or Arizona (excluding the Navajo Nation), which apparently don’t take part in this bizarre ritual. This is marginally better than ancient Greece, where adjacent cities kept separate and discoordinated calendars even though their sundials might have remained in sync.

While Macs should take this all in their stride, there’s one feature that twice every year throws its hands up in horror leaving you to work around it, the log show command. Whatever you’re doing in the small hours when the clocks go back or forward, don’t try accessing log entries written during those couple of hours or you could be sadly disappointed.

When clocks go forward in the Spring, log show just skips an hour, leaving a void in the fabric of time. But when they go back, a whole hour occurs twice, and wreaks havoc with the log. That’s another time feature subject to general disagreement, when to change to and from summer or daylight saving time. In the UK and Europe, that’s undertaken at 01:00 UTC (or, in the UK, GMT), while in the US it’s at 02:00 local time. It’s surely confusing enough that clocks change simultaneously across the whole of Europe, but to know when those in a US state are due to change you also have to know the local time before they change.

To see how bad this is, after the dust had settled on the system clocks of two of my Macs last Sunday, I dared to look with two log browsers, Ulbow that relies on the log show command, and LogUI that has better sense and calls the OSLog API direct.

Accessing the log using Ulbow, there was no problem around 02:00 or 01:00 GMT (if you must, UTC), when you might have expected the clock change to have had greatest impact. On both Macs running here at the time, it was exactly 01:49:02 GMT or BST that the log fell over. Calling for a single second of the log at that moment elicited over 300,000 entries on one Mac, and just short of four million on the other.

Whatever logoclysm strikes at that moment is over in the twinkling of an eye. Step back a second or two and you’ll see normal log entries reported in the previous time (here, BST +0100), and step forward to see everything orderly and in new time (GMT +0000). Use LogUI instead of Ulbow, though, and you can’t even tell when local time was adjusted, as that app expresses all times according to the prevailing setting at the time you read the log.

There is a seldom-used option for the log show command in -timezone local, which displays all times in the current local time. Yet the default is for log entries to be “displayed in the timezone at the time the entry was written to source archive or file”, as explained in man log. In some circumstances that may make entries more readable, but at least twice a year it causes chaos, and I’m puzzled why log show still makes that its default.

Although Apple doesn’t document it, I suspect that the Unified log, like other time-reliant subsystems in macOS, relies on Mach ticks since a clock datum. Because those are strictly monotonic, they can’t go backwards and cause the confusion seen here, unless of course you disable network time syncing and manually set your Mac’s clock to a time in the past (and even that is appearance rather than reversal). That used to occur on old Macs whose system clock relied on a small internal battery with a limited life. When that battery expired, the system date and time reverted to the datum of 1 January 1970, at the time the mark of a Mac that needed its battery replaced.

If you’re in the US, I wish you a smooth transition when your clocks go back this weekend, and hope you don’t need to access any entries in the log for the hour that time is out of joint.

If you’ve read any of my articles retelling narratives like Dante’s Inferno, you’ll be familiar with the illustrations of Gustave Doré (1832–1883), who is among the most prolific and famous in Europe. His prints overshadow his paintings, the subject of this and tomorrow’s article, and he was also a sculptor. Some of his landscapes are outstanding, but as they were produced during the era of Impressionism have been cast aside by history. In these two articles I concentrate on his narrative oil paintings, for if anyone understood narrative art, it should surely be such a prolific and successful illustrator.

Doré was a precocious child, and started his career as a caricaturist for a newspaper at the age of 15. By the 1850s his illustrations were being commissioned by major publishers in both France and Britain, including those for a new illustrated English Bible. Here are two prints from that work published in 1866.

The first shows the popular story of Judith and Holofernes; Doré avoids the most powerful scene of the decapitation itself, but follows the more guarded approach adopted by Etty and others, to make it more acceptable to a Victorian publisher.

His Death on the Pale Horse, accompanying the book of Revelation 6:8, remains one of the most popular and perhaps iconic portraits of the ‘Grim Reaper’, whose visits to families were all too frequent at the time.

Doré first illustrated Dante Alighieri’s Divine Comedy as early as 1857, and returned to it in the mid 1860s. He painted several works derived from the first part Inferno. This describes Dante becoming lost in a wood and unable to find the way to salvation. He is rescued by the classical Roman poet Virgil, and the pair then descend and travel through the underworld together. By convention, Dante himself is shown dressed in red robes with a distinctive hat, and Virgil with a laurel wreath on his head.

When he reaches the foot of a hill, Dante sees its upper slopes already lit by the first rays of the sun. As he starts walking up, his way is blocked first by a leopard, then by a lion, and finally by a wolf.

The sinners in hell are divided according to the type of sin; in this oil painting, Doré shows Virgil (left) and Dante at the last of these ‘circles’, the ninth, for those who committed sins of malice, such as treachery. These sinners are shown partially frozen into an icy lake, with additional blocks of ice scattered around, just as described by Dante.

Among the side-stories related by Dante is that of Paolo and Francesca da Rimini, who are in the second circle for sins of lust. She committed adultery with her husband’s brother, Paolo Malatesta. Her husband Giovanni (or Gian Cotto) then killed them both. In this oil painting Doré shows the lovers, Francesca’s stab wound visible near the middle of her chest, Paolo’s still bleeding, as they are blown around and buffeted for their sins. At the lower right he shows Dante and Virgil looking on. This was first shown at the Salon in 1863, and was praised highly by the critics.

Doré also illustrated Miguel de Cervantes’ Don Quixote in a lengthy set that has been used by others as the basis for further illustrated editions.

When the newlyweds Basil and Quiteria entertain Don Quixote and Sancho Panza for three days, they visit the Cave of Montesinos and the Lakes of Ruidera nearby. To mark this well-known episode, Doré painted this non-narrative scene of Don Quixote and Sancho Panza Entertained by Basil and Quiteria in oils in about 1863.

Many of Doré’s easel paintings were independent of his illustrations.

One of the few paintings that I have seen that captures the experience of dense clouds of butterflies is his Summer from about 1860-70. Set in what appears to be an upland or alpine meadow, its butterflies look like large flowers that have taken to the air.

Between Sky and Earth (1862) remains more of a mystery. The viewer is high above the fields outside Doré’s native Strasbourg, where several small groups are flying kites. The kite shown at the upper left has just been penetrated by a flying bird. Another unseen kite, off the top of the canvas, has a traditional tail, at the end of which is tied an anxious frog by a hindleg. However, a stork appears to have designs on seizing the opportunity to eat the frog, and is approaching from behind, its bill wide open and ready for the meal.

This could be an allegory, of course, but is probably a humorous depiction of kite-flying at the time, when people were still puzzled as to what happened to living creatures as they ascended higher in the atmosphere.

By the late 1860s Doré was tackling more heavyweight narratives on very large canvases. The Triumph Of Christianity Over Paganism (c 1868) has become as elaborately symbolic as the paintings of the younger Gustave Moreau. In the upper part of this painting, Christ, bearing his cross, is surrounded by an angelic host flying out, swords drawn and shields borne, to fight the pagan evils on the earth below. Among those are recognisable gods of the Classical pantheon, with Zeus/Jupiter at the centre, holding a thunderbolt in his left hand.

In his humorous Evening in Alsace from 1869, four young men are squeezed into an open window as they try to charm the four young women standing below. Along comes a flock of geese to join in and ruin their chances.

Thanks to your overwhelming response to my appeal for information about CPU core frequencies in M3 Ultra and M5 base chips, this article updates the data to cover those new models in addition to all previous M-series chips.

Performance (P) and Efficiency (E) CPU cores in Apple silicon Macs are run at a range of different frequencies so they can deliver optimum performance with a minimum power and energy use. Cores are grouped into clusters of 2-6, and macOS sets the frequency of each cluster according to workload, Quality of Service, power mode and thermal status. Maximum frequencies differ according to the family, variant within that family, and between E and P cores. Current values are:

• M1 E 2064 MHz or 2.1 GHz; P 3228 MHz or 3.2 GHz;
• M2 E 2424 MHz or 2.4 GHz; P 3696 MHz or 3.7 GHz;
• M3 E 2748 MHz or 2.7 GHz; P 4056 MHz or 4.1 GHz;
• M4 E 2892 MHz or 2.9 GHz; P 4512 MHz or 4.5 GHz.
• M5 E 3048 MHz or 3.0 GHz; P 4608 MHz or 4.6 GHz (base variant only).

As Pro and Max variants may have higher frequencies than base variants, it’s likely that future M5 Pro or M5 Max chips will be able to run their P cores at a higher maximum frequency than today’s base M5 chip.

The full table of frequencies reported by powermetrics is:

This is available for download as a Numbers spreadsheet and in CSV format here: mxfreqs1025

Earlier this year I published a detailed analysis of frequencies in the M1 to M4 families. The only addition to those is the M3 Ultra, whose frequencies are the same as those of the M3 Max, so they haven’t changed. The remainder of this article concentrates on the base variant in each family, from M1 to M5, the chips that power the most popular models and set the standard for what most folk will experience.

Frequency range

Over the last five years and five families of chips, their frequencies have increased steadily, as shown in the charts below. Each bar in those charts spans the range of frequencies from minimum (idle) to maximum, for the base variant in that family.

Idle frequency in E cores has risen from 600 MHz to 972 MHz, a rise of over 60%, and their maximum frequency has risen from 2064 MHz to 3048 MHz, a rise of nearly 50%.

P cores have seen more substantial change. Their idle frequency has risen from 600 MHz to 1308 MHz, a much larger rise of nearly 120%, and their maximum frequency has risen from 3204 MHz to 4608 MHz, just under 50%. The M5 is notable for its greater rise in idle frequency, and lesser rise in maximum frequency.

Frequency steps

Rather than macOS set an arbitrary frequency, it selects one from a list of steps that are distinctive to that family and variant. Looking at the table of frequency steps it might be easy to assume those numbers are chosen arbitrarily, but when expressed appropriately I think you can see there’s more to them.

To look at frequency steps and the frequencies chosen for them, let me explain how I have converted raw frequencies to make them comparable.

First, I work out the steps as evenly spaced points along a line from 0.0, representing idle, to 1.0, representing the core’s maximum frequency. For each of those evenly spaced steps, I calculate a normalised frequency, as
(Fmax – Fstep)/(Fmax – Fidle)
where Fidle is the idle (lowest) frequency value, Fmax is the highest, and Fstep is the actual frequency set for that step.

For example, say a core has an idle frequency of 500 MHz, a maximum of 1,500 MHz, and only one step between those. Its steps will be 0.0, 0.5 and 1.0, and if the relationship is linear, then the frequency set by that intermediate step will be 1,000 MHz. If it’s greater than that, the relationship will be non-linear, tending to a higher frequency for that step. The following charts compare those normalised frequencies with steps evenly spaced between idle and maximum frequencies.

This chart shows normalised frequencies and steps for E cores in base M1 and M5 chips, the latter in red. It shows how, over those five years, the number of steps (available frequencies) has increased. In the M1, the frequency selected in the middle of its five steps was half-way between idle and maximum. Not only does the M5 have more intermediate frequencies available, six instead of three, but frequencies used in the upper half of its steps are higher than in the M1 (when normalised).

This tends to boost higher frequencies used for running threads that can’t be accommodated on P cores, while running background threads at slightly lower frequencies than would be expected when at frequencies close to idle, as they are.

These curves have undergone evolution across different families, as shown here in a composite of the curves for all five families. The red curve of the M5 deviates more from the M1’s straight line of identity than any of the others, particularly at the top end.

The equivalent comparison between frequencies of P cores in M1 and M5 chips shows a different picture. The M1 is again the simpler, being linear until it reaches a step of 0.8, while the M5 has higher frequencies in all except the top few values.

Shown here alongside curves for all earlier families, the red curve for the M5 has higher frequencies for every step apart from the last few.

Taken with the trends seen in the frequency ranges (bar charts above), these demonstrate that the M5 is designed to improve performance by increasing the frequencies used to run threads with higher Quality of Service, as opposed to background threads.

Conclusions

• CPU core frequencies in the M3 Ultra are the same as the M3 Max.
• The base M5 continues the trend for higher frequencies in both E and P cores, with a marked rise in P core idle frequency.
• More subtle changes in intermediate frequencies boost them for higher frequencies of E cores, where they’re likely to improve performance of threads overflowed from P cores.
• Intermediate core frequencies continue to be selected to optimise performance and power use.

Of the several hundred landscape painters of the Dutch Golden Age, the best-known and most influential is Jacob van Ruisdael, whose paintings were described by Vincent van Gogh as “sublime”. Van Ruisdael was starting his career just as Nicolas Poussin was reaching his zenith in Rome, and the two were major influences on all subsequent landscape artists, particularly Thomas Gainsborough, John Constable and JMW Turner.

Jacob Isaackszoon van Ruisdael (1628/9-1682) was born in Haarlem into a family of painters. Presumably apprenticed within the family workshop, he was admitted to the local Guild of Saint Luke in 1648, and from the outset appears to have specialised in landscape painting.

Van Ruisdael’s earliest landscapes contained trees, as they would at a time when trees and woods were more extensive in their coverage across the whole of Europe. The view in Landscape with a Church (c 1645) looks familiar, as its composition was used by Gainsborough, Constable, and many other later artists. Prominent at the left, and forming repoussoir, is the hulk of an old tree, younger branches sprouting from the remains, a recurrent theme in Gainsborough as well as van Ruisdael. A recession in depth on the right leads to the brighter-lit church in the middle distance.

The trees here are painstakingly constructed from the anatomy of their branches, with leaves painted individually in the foreground, but delicately en masse in the further distance. Bark colour, texture, and rich lichen growth are also shown in fine detail.

Van Ruisdael soon showed a deep understanding of the stages in the life and looks of oak trees. In Road through an Oak Forest (c 1646-7) he captures the later life of a stag-headed oak, that long ago lost its crown, on the left, a flush of new growth on a fallen trunk, and another still clinging onto life despite a great split at its base.

Judging from the girth of their trunks, the oak trees shown here are around 400 years old, making it likely that they were saplings in the thirteenth century, possibly even earlier. They form a remarkable window back in time to the late Middle Ages.

Some of van Ruisdael’s sketches and drawings have also survived, among them Landscape with a Stone Bridge (c 1647). This shows his development of foliage from branch structure quite clearly, and the fact that he didn’t block in that foliage, preferring gestural squiggles and other marks.

Van Ruisdael was a faithful observer of the different species of tree and their forms, as shown in his timeless A Wooded Landscape with a Pond from about 1648. He has maintained careful, anatomical construction even in the prominent tree at the centre right, in the middle distance, and the canopies appear light and leafy.

Gentle rural decay is shown not only in the ruined buildings in Landscape with a Mill-run and Ruins (c 1653), but also in the stag-head tree in the centre of the painting.

He moved to Amsterdam in 1657, to take advantage of its growing prosperity. He appears to have travelled little, remaining within the European lowlands and venturing only just over the border into Germany. His only known student was Meindert Hobbema, who became an accomplished landscape painter who also depicted trees as important elements within his works.

Probably painted soon after he had moved to Amsterdam, The Great Forest (c 1655-60) shows travellers along a track passing at the edge of an ancient woodland, with an assortment of trees in various states of advancing age, including some reduced to stag-heads.

The upland landscape shown in The Forest Stream (c 1660) was clearly not one that van Ruisdael had ever seen, but must have been composed from studying the paintings of others, and talking to those more widely travelled. His trees remain much as before, with a gnarled and twisted stag-head at the right, and at the left a near-dead trunk poised in slow-motion collapse into the stream.

Although most of van Ruisdael’s paintings are in full daylight, as with his contemporaries he also explored more transient light effects, in A Marsh in a Forest at Dusk (c 1660). Now the ancient trees launching themselves out from the bank at the right have engaged with those growing in the marsh. The effect of the late dusk light on their canopies is spectacular, as are the thin banks of cloud above, lit by the setting sun. His careful leaf-by-leaf depiction of canopies of different tree species generates distinct and life-like textures.

In Landscape with Waterfall (c 1660-70), van Ruisdael revisited the distant church framed by nearer trees theme of Landscape with a Church above. Perhaps this time the church is a little too far away, though still an inspiration to Constable and Gainsborough. At the right a birch collapses off the edge, and there is a pair of ancient wizened oaks filling the centre.

He continued to develop the theme of old oaks and water in Oaks at a Lake with Water Lilies in about 1665. Again a dying ancient hulk stands like a prow from the bank at the left, and he shows bright flowers on the water-lilies.

Many of his woods are either unpopulated, or the few people providing staffage are barely visible against their surroundings. His undated A Road through an Oak Wood is different, with a couple of travellers on its road, and woodland activities of clearing and burning at the left.

The Golden Age was primarily based on prosperity from trade, not home production, but increasing demand from the affluent cities led to greater timber production, particularly for ships and buildings, and the clearing of woods to augment farmland.

My final selection is perhaps his most detailed essay on the effects of advanced age on trees, Three Great Trees in a Mountainous Landscape with a River (c 1665-70). Although the mountains are borrowed or imaginary, the three trees of the title seem almost impossibly intertwined. The nearest is struggling to survive, remains of its former glory resting, limbs in the air, at its foot.

When the Dutch economy collapsed in 1672, he appears to have remained relatively prosperous, and continued to work in Amsterdam until his death a decade later, in 1682.

References

Wikipedia
Slive, S (2005) Jacob van Ruisdael: Master of Landscape, Royal Academy of Arts, London. ISBN 978 1 903973 24 0.
Ashton, PS, Davies, AI & Slive, S (1982). “Jacob van Ruisdael’s trees”. Arnoldia 42 (1): 2–31; available from JSTOR.

Last week I drew attention to problems interpreting the timestamps of files in macOS, generating lively discussion with Chris and Richard. Although the gist of that article stands, it was clear that there remained several issues, and this sequel tries to address those better, with the aid of a new app, Dropera 2. The TL;DR for this article is that timestamps are even more complicated than I previously described.

The first task was to develop a tool for reading and recording these timestamps reproducibly. Although the four key timestamps are exposed in Precize, opening a file in that app is likely to change at least one of them. For a substitute I turned to an earlier SwiftUI demo, Dropera, with its drag-and-drop support to handle file URLs without opening, reading or otherwise changing the file.

Timestamps

This new version of Dropera had then to read the right timestamps and convert them into accessible dates and times. For some timestamps, we’re spoiled for choice: time of creation of a file, shown in the Finder as Date Created, is saved in an APFS file’s attributes as create_time, exposed in the stat command as st_birthtime, and accessible within an app’s code as the NSFileCreationDate file attribute or creationDate URL resource. To establish which timestamp is which, I have compiled a table giving the sources I have been able to discover.

For Dropera, following careful comparison with the values delivered in stat, I selected:

• Creation from NSFileCreationDate
• Modification from NSFileModificationDate
• Attribute modification from attributeModificationDate
• Access from contentAccessDate.

The last two aren’t available in the Finder or elsewhere in the GUI, while the Finder does provide Date Last Opened, Date Added and Content Created:

• Date Last Opened isn’t related to Access Time, but is recorded in the com.apple.useddate extended attribute. Unfortunately, adding and manipulating that may change the Attribute Modification timestamp, so has to be avoided. As Apple doesn’t appear to document the xattr or its interpretation, I have avoided looking at it any further here.
• Date Added is the timestamp when a file was added to its current directory. As that isn’t strictly speaking a file attribute, I will ignore it here.
• Embedded records of Content Created require file data to be read, so accessing them is likely to update at least one of the key timestamps.

Each of those three is available from the metadata indexed by Spotlight, but that’s an indirect and unreliable way to access them.

Using Dropera

To use Dropera to read the four key timestamps just drop the file onto its window, and the app will then display the filename, its path, and the four timestamps in the order of Creation, Modification, Attribute modification and Access times.

Adjust the window width to make these most convenient to read. The layout shown above is compact and automatically splits each timestamp into date and time components. In other uses, you might prefer to widen the window so each entry takes a single line.

To refresh the values shown for the current files, click on the Refresh tool. Although the window continues to display just the single set of entries, the previous timestamps are saved in memory, and the whole history since the last drag-and-drop onto that window can be exported to a text file using the Save as text tool. You can also select the line of results, copy and paste that into another app if you prefer.

Drop multiple files onto Dropera’s window and all their timestamps will be shown. You can then select continuously (Shift-click) or discontinuously (Command-click) to copy those values, and Refresh them.

Demonstration

Open TextEdit, create a new file and set its type to plain text. Add a few words and save it somewhere convenient. Then open Dropera, and drop that file onto its window to inspect its timestamps. They’re likely to show Creation and Modification times the same, Attribute modification slightly later, and Access another second or so afterwards.

Next make a small change to that document and save it. Click Dropera’s Refresh tool and only the Creation time remains unchanged. Close that document in TextEdit, and Refresh the times again to confirm that none have changed. Now select the file in the Finder so its QuickLook thumbnail is previewed. When you Refresh its times, you should see its Access time has been updated. Now double-click the file to open it in TextEdit, and check times again while the file is still open. Attribute modification and Access times are altered, but remain the same after you have closed the document. Export those records as a text file, and you should see:

• Creation time remains unchanged throughout.
• Modification time changes once, when the second version was saved.
• Attribute modification time changes twice, when the modified file was saved, and when the file was reopened.
• Access time changes three times, the additional occasion being when you viewed the document’s thumbnail in the Finder.

Dropera 2, which requires macOS 14.6 or later, is available from here: dropera20

Enjoy!

Since ancient times people have written, drawn and painted using pigments and dyes in water, often without any binder to adhere them to the ground. These are generically termed inks, and distinct from other media such as watercolours or the temperas. Most common among them is India ink, whose essential ingredients are carbon particles from soot, suspended in water. When applied to a suitably absorbent ground that has stood the test of centuries.

Hieronymus Bosch’s study of The Owl’s Nest from around 1505-1516 is a good example of a pen and ink drawing starting to transcend into painting.

Washes applied using a brush became common in sketches made in front of the motif, such as Egbert van der Poel’s Fire in the Nieuwe Kerk, Amsterdam, in 1645. Known for his paintings of fires, he used these sketches to paint his famous brandjes in the studio. Landscape artists such as Nicolas Poussin and Claude Lorrain used the same sketching media working en plein air to build image libraries for the idealised landscapes used in their finished paintings.

By the early nineteenth century, artists like Samuel Palmer were creating works that are to all intents and purposes full-blown paintings using black and coloured inks, such as this atmospheric nocturne of Cornfield and Church by Moonlight from about 1830.

Used without a binder, inks normally rewet and smudge or blur, so have to be applied after any watercolour. Adding a binder such as shellac to India ink makes it waterproof when it has dried, and this was used in combination with watercolours by illustrators and painters such as the great Arthur Rackham, here in one of his illustrations for an edition of Charles Dickens’ A Christmas Carol.

A related medium that also crossed over from drawings and illustrations into paintings is casein, a protein-based tempera. It too has a long history, but didn’t become popular among artists until the late nineteenth century. Casein is a protein originally obtained from sour milk, but by the nineteenth century it was more usually prepared by the addition of rennet, enzymes used in cheese manufacture, extracted from the stomachs of calves.

Casein powder is then turned into paint by dispersion in an alkaline solution, typically made from lime or borax, and pigment is ground in. When lime is used the paint works best on porous grounds, but must be used fresh. When a little linseed oil is added to borax casein, a shelf-life of several months or more is possible. Casein paints dry as quickly as egg tempera, but can be reworked for a period until their binder has fully hardened. Once that has taken place, their paint film is robust and stable.

The earliest painting I have seen that is known to have been made using casein paints is William Morris Hunt’s unusual view of Niagara from 1879. Hunt deviated here from his customary use of oils, although he still applied his paint to a prepared canvas support.

One of the most famous artists to have used casein paint is Gustav Klimt. In 1902, he used it in a frieze of 24 metres (nearly 80 feet) length for the fourteenth exhibition of the Vienna Secession, his Beethoven Frieze, of which that above is a section known as The Hostile Powers, and that below is Nagging Grief. He applied his casein paint directly onto mortar with added stucco, gold leaf, and other materials. This is known to be a robust form of wall-painting that is much more accommodating than fresco, and just as enduring, but has never become popular.

A few of Colin Campbell Cooper’s skyscraper cityscapes were painted using casein media, including this view of Flatiron Building, Manhattan from about 1908. He was equally proficient in watercolour and oils, and I don’t know why he experimented with casein, nor why he used it so infrequently.

Another Vienna-based artist, Albin Egger-Lienz, also used casein on occasion, here in this fourth of several different versions of Totentanz (Dance of Death) from 1915.

During the twentieth century, casein paints didn’t become popular but continued in use, particularly by those who also made illustrations. Just when they were attracting a following among artists such as Andy Warhol, they were rapidly displaced by acrylics. Despite that, casein paint is still available today, sold by Pelikan under the brand name of Plaka.

Apple silicon chips are designed to minimise the power and energy they use without compromising their performance. One of the many tricks they use is to run the cores in their CPUs at variable frequencies, and in more recent models to shut down those cores they don’t need. At the start of the year, thanks to the many who contributed information about their Macs, we were able to assemble a table of CPU core frequencies for all the M-series chips then available. Those demonstrated that frequencies differed between families such as M1 and M2, and between models within each family such as M2 Pro and Max, as well as between P and E cores.

Since then Apple has released two new chips, the M3 Ultra available in the current Mac Studio, and most recently the base M5 that has recently been impressing so many. This article briefly reviews what we know about CPU core frequencies, and appeals for information about those two new chips.

The best way to discover which frequencies are supported by the P and E cores in the CPU of an Apple silicon chip is using the output of the command tool powermetrics. This lists frequencies for P and E cores, and this article assumes that those it gives are correct. Although it’s most likely that these frequencies aren’t baked into silicon, so could be changed, I’ve seen no evidence to suggest that Apple has done that in any release Mac.

Frequencies

If powermetrics is to be believed, then the maximum frequencies of each of the CPU cores used in each generation differ from some of those you’ll see quoted elsewhere. Correct values should be:

• M1 E 2064 MHz or 2.1 GHz; P 3228 MHz or 3.2 GHz;
• M2 E 2424 MHz or 2.4 GHz; P 3696 MHz or 3.7 GHz;
• M3 E 2748 MHz or 2.7 GHz; P 4056 MHz or 4.1 GHz;
• M4 E 2892 MHz or 2.9 GHz; P 4512 MHz or 4.5 GHz.

However, not all variants within a family can use those maximum frequencies. The full table of frequencies reported by powermetrics is:

This is available for download as a Numbers spreadsheet and in CSV format here: mxfreqs

Why those frequencies?

Depending on workload, thread Quality of Service, power mode, and thermal status, macOS sets the frequency for each cluster of CPU cores. Those used range between the minimum or idle, and the maximum, usually given as the core’s ‘clock speed’ and an indication of its maximum potential performance. In between those are as many as 17 intermediate frequencies giving cores great flexibility in performance, power and energy use. Core design and development uses sophisticated models to select idle and maximum frequencies, and evidently to determine those in between.

Looking at the table, it would be easy to assume those numbers are chosen arbitrarily, but when expressed appropriately there are patterns. Apple’s engineers have clearly put considerable effort into picking optimised frequencies for each of the families and variants within them. If you think this is fine detail and only the maximum frequencies count, then bear in mind that both P and E cores spend a lot of their time running at those intermediate frequencies.

How to report frequencies

If you have a Mac Studio M3 Ultra or MacBook Pro M5 you can add to this collection, please open Terminal and run the command
sudo powermetrics -n 1 -s cpu_power
which then prompts you for your admin password. A few seconds later the window will fill with a single set of measurements looking like this:

All I’d like is a copy containing 3 lines from that:

• Machine model at the top, to tell me which Mac it is, thus which chip.
• E-Cluster HW active residency, which contains a list of frequencies for the E cores.
• P-Cluster HW active residency, which contains a longer list of frequencies for the P cores.

To help, I have highlighted those three lines in the screenshot above.

Thank you.

After meeting some political traitors, Dante and Virgil have come across Count Ugolino, who is gnawing the back of the head of Archbishop Ruggieri as a dog chews a bone. Their story is one of the most famous and horrific in the whole of the Divine Comedy.

Ugolino raises his mouth from the cleric’s head and wipes his lips on his victim’s hair. He then introduces himself and the Archbishop. He explains how he, a leading politician at the time, was imprisoned with his young sons and left to starve to death. In his hunger he tried gnawing his own hands, but his sons suggested that their father should eat them instead.

This glue tempera painting by William Blake is one of the few that isn’t taken from his last works illustrating the Divine Comedy, but is a prior work. Unfortunately, its equivalent in Blake’s last series got no further than a pencil sketch before the artist’s death.

Ugolino stopped gnawing his own flesh, and sat in silence day after day, watching his sons die in front of him. By the time the last was dead, the Count himself had gone blind. Once confident there was no life left in their bodies, his hunger overcame his grief.

In history, Ugolino was born into a Ghibelline family in the city of Pisa. He soon changed allegiance to the Guelphs, whom he helped in their quest for power in Pisa. When that was unsuccessful, the Count was imprisoned and exiled, but later led Pisan naval forces against its rival Genoa, for which he was made Pisa’s leader.

In an act of political expediency, Ugolino then handed over Pisan castles to Lucca and Florence, following which he conspired with Ghibellines including Archbishop Ruggieri. This backfired on him, and the Archibishop had him imprisoned with his two sons, two grandsons, and another young man. After eight months there, the door was locked and nailed shut, and its key thrown into the river. Ugolino and the five young men died fairly quickly of starvation.

As far as I’m aware, this painting of Count Ugolino and his Children in the Dungeon is the only work by Joshua Reynolds taken from Dante’s Divine Comedy. Exhibited at the Royal Academy in 1773, nearly five hundred years after the death of the Count, I’m not aware that Reynolds had access to any contemporary images of his subject.

It’s therefore revealing that this slightly later copy was one of many images of the faces of the famous and infamous on which Lavater based his textbook of physiognomy, which in turn was popular among painters, making it a self-fulfilling fantasy.

Dante and Virgil move on from Ugolino’s tragedy to meet more traitors frozen into Lake Cocytus in Hell, as they make their way towards the bottom of its pit, and Lucifer himself.

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.

Pierino da Vinci (1530–1553) was an Italian Renaissance sculptor, the son of Leonardo da Vinci’s younger brother. He died of malaria, which was still endemic in much of Europe at that time, at the age of only 23, leaving few examples of his work.

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, first published in 1857 and still being used. These were followed in 1867 by more illustrations for Purgatorio and Paradiso. This article looks at his paintings.

Joseph Anton Koch (1768-1839) was an Austrian landscape painter, who worked mainly in Neoclassical style. During his second stay in Rome, he was commissioned to paint frescos in the Villa Massimi on the walls of the Dante Room there, which remain one of the most florid visual accounts of Dante’s Inferno. He completed those between 1824-29. He also appears to have drawn a set of illustrations for Dante’s Inferno in about 1808.

Johann Caspar Lavater (1741-1801) was a Swiss poet and philosopher who was a friend of the painter Henry Fuseli. Between 1775-78, he published an early textbook on physiognomy, in which he related physical appearance, particularly of the face, to specific character traits of individuals. He did this using many illustrations of famous and infamous people. This attracted a popular following, including many artists.

Sir Joshua Reynolds (1723–1792) was the major portrait painter of his day, one of the co-founders and first president of the Royal Academy of Arts in London. He enjoyed royal patronage, and moved in the highest of artistic circles. However, his work and teaching were lambasted by William Blake, and some of his paintings have suffered serious problems in their paint layer as a result of his experimentation with pigments and technique.

Jan van der Straet, also commonly known by his Italianised name of Giovanni Stradano (1523-1605), was a painter who started his career in Bruges and Antwerp in Belgium, but moved to Florence in 1550, where he worked for the remainder of his life. Mannerist in style, he worked with printmakers in Antwerp to produce collections of prints, including an extensive set for The Divine Comedy.

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 331. Here are my solutions to them.

1: A red Canadian named by Jef and after John came in 1984.

2: A wonder for cooking led by Larry came in 1993.

3: This fruit from Newtown flopped between 1996-97.

The common factor

I look forward to your putting alternative cases.

For much of the last 25 years, macOS has had ill-defined and pervasive problems that have often been attributed to incorrect permissions in various parts of the file system. As a result, one of the common panaceas has been to repair those permissions, using procedures that have changed over those years.

Repair disk permissions

Until the introduction of System Integrity Protection (SIP) in 10.11 El Capitan, these problems generally resulted from files within the system acquiring incorrect permissions. To address this, Disk Utility had a feature to check and repair permissions of all major parts of the system, based on information contained in BoM files for system updates and installations. Repairing permissions in this way became one of the main panaceas in those older versions.

Although primarily intended to deliver better security protection, one of the benefits of SIP was that it largely prevented system files from gaining incorrect permissions, and the feature to repair them was removed from Disk Utility. In any case, because of SIP it was no longer possible for Disk Utility to change the permissions of files that were protected by SIP.

Reset user permissions

When macOS 10.12 Sierra was released, a different problem appeared, in which permissions were apparently set incorrectly not in system files generally, but in the user’s Home folder, specifically in ~/Library/Preferences. To address this Apple added a new verb to the already complex command tool diskutil, resetUserPermissions, and described how to use this in a support note. It’s perhaps no coincidence that this new problem appeared at about the same time that the cfprefsd service took on management of those preference files, and just one year after repairing disk permissions ceased.

At that time, the following problems were attributed by Apple to incorrect permissions in ~/Library/Preferences:

• changes to preference settings, particularly those for System Preferences, do not ‘stick’;
• changes made to the Dock do not ‘stick’;
• you are asked to authenticate when trying to move or alter some folders in your Home folder;
• when trying to save, you are told that the file is locked, or that you don’t have permission;
• Preview, TextEdit, and App Store apps (which are sandboxed) may crash when opened;
• alerts appear warning that the startup disk has no more space available for app memory;
• Safari or SafariDAVClient use large amounts of resources (memory);
• the Mac runs very slowly;
• iTunes cannot sync a device;
• there are problems with Photos or iPhoto libraries, including inability to import into the library, or forgetting the library each time the app is opened.

Most if not all of those could have been attributable to problems resulting from bugs in cfprefsd.

Repair Home permissions

Five years ago, Apple changed its recommendations to include running a new tool repairHomePermissions in Recovery mode, then re-installing macOS. Shortly afterwards, when Big Sur was in beta in June 2020, Apple withdrew that support note and all reference to repairing permissions, although the tool is still available in Recovery mode even on Apple silicon Macs.

Running repairHomePermissions from Terminal in Recovery launches a GUI app to repair permissions on a selected Home folder on the Data volume. However, I strongly recommend that you don’t try using this, as you’ll end up with the user being locked out of every folder in their Home folder. I have tried it three times in virtual machines, and each time I have had to discard that VM because of the problems it caused.

Delete a corrupt preference file

Regardless of those, there are still occasions when preference files can cause problems. These typically occur when a corrupt or damaged preference file causes an app or other code to crash, usually when it’s being launched. Although these are now far less common, and the SSV ensures that system files can’t become corrupted as they did in the days before SIP, it’s useful to know how to deal with them.

On most occasions, a preference file can be deleted in the normal way, either in Finder or Terminal, and it won’t return until that app is run again, as it won’t currently be managed by cfprefsd. The alternative is to use defaults:
defaults delete com.mycompany.appname
deletes all the key-value pairs within the preference file for com.mycompany.appname, leaving just the empty property list. This has the advantage that it can be used when cfprefsd is managing that file’s contents, so should always be reliable. Provided the app handles preferences correctly using UserDefaults, it should be able to repopulate the empty property list the next time that app is launched.

One significant caution is when working with files inside ~/Library/Containers,~/Library/Group Containers,~/Library/Daemon Containers and similar managed folders. Because these form sandboxes, macOS manages them differently and tampering with their contents is likely to have unintended effects, so is best avoided, although the defaults command should still be safe.

Summary

• Repairing disk permissions on system files ceased with SIP in El Capitan.
• Repairing permissions on Home folder preference files is no longer recommended by Apple, since Big Sur.
• Safe and robust deletion of contents of a preference file can be performed using defaults delete.
• Don’t tamper with files inside ~/Library/Containers, ~/Library/Group Containers and similar folders.
• Never be tempted to run repairHomePermissions in Recovery mode.