Monday’s xkcd made an interesting point:

I’ve sometimes asked people to imagine that they had an expandable ruler.  If an object measured as longer than they expected, they could add a centimeter or two to the ruler to match their expectations.

Such a ruler would not be much of a measuring device.  Likewise, the calendar, with its expandable and contractible bits, its subdivision into the week, which is not commensurable with the other major subdivisions of the calendar, its months of varying lengths, etc, is not particularly satisfactory as a measuring device.  Indeed, if its chief purpose were to serve as a measuring device, it would have been replaced long ago.

What a calendar chiefly is, is a series of commands.  Many of these commands are tied to specific events in nature, and so we resort to leap days and the like to ensure that they come up at reasonable times.  That today is 22 April means, in much of the world, “Observe Earth Day!”*  That yesterday was 21 April meant, to Latin teachers, that it was Foundation of Rome Day, and so they have to organize some cheesy kind of classroom activity, possibly involving togas.**  That tomorrow is 23 April means, to Christians in certain categories, that it will be Saint George’s Day and so they ought to do whatever it is they do to commemorate Saint George.***

*xkcd fans will understand me when I say that my first reaction to this command is to resolve that I will not be going to space today.

**I am a Latin teacher, but I teach in a college, and I don’t have language classes on Tuesdays.  So I got out of it.

***I recently assigned myself in one of those categories, and I value Saint George for various reasons.  First. as a soldier who was put to death for refusing an unjust command, his memory should give courage to others whose consciences urge them to say no when it might be easier to join in atrocities, such as Albert Battel or Hugh Thompson.  Second, as a saint revered in all the major communions of the East and also in parts of the West, George is a potent symbol of Christian unity.  Third, the particular category of Christian I’ve ended up in is Anglicanism, and that’s one of the Western churches where Saint George has played a special role.  And fourth, my grandmother was born on 23 April, so I like to make a fuss about something on of that day.