Days, weeks, months, years.

Which of these units of time is not like the others? Weeks! Weeks have no astronomical basis. So why do we have weeks? What are weeks for? Why 7? Because it was written in the Bible. Perhaps hardcore atheists should object to this sevenness.

There were rival weeks, both ancient and modern, including short or long weeks corresponding to market days in some agricultural societies, 10-day weeks in revolutionary France and both five- and six-day weeks in Stalinist Russia.

6?! That's just crazy. I can see wanting to go to 10, but 6? That's just perverse. But there's not much point trying to go all metric with 10, because days and years are determined by overwhelming astronomical facts.

Still, I wonder how different we would be if we hadn't settled on these cycles of 7 days. The rhythm of weeks shapes our moods and activities. We keep going through this short arc of ambition. Tuesdays are crucial, you know? Get cracking! If things don't happen on Tuesday, you feel like giving up. I mean there will be some chance to salvage the week on the Wednesday, but you'll have to do it under the weight of a failed Tuesday.

Man, it's Tuesday. Tuesday! Don't you understand about Tuesday?

But if we had a 10-day cycle, the second day would be just a smooth acceleration day. The third day would have more oomph. The fourth day would add room to really develop the week's accomplishments. Ah, how much potential life would contain, how effective I would be, if only those French revolutionaries had gotten their way!

Shut up! It's Tuesday! Get out of here! I can already see the gaping maw of defeat that is Thursday!