This is a cross-post from Nextdoor.
subject: why the calendar doesn't begin on the solstice
An online friend of mine wrote this brief history of the modern calendar in an attempt to answer that question (CW: occasional stylistic cursing): https://gist.github.com/joyeusenoelle/3754e00a37fe81aa43aad3eb9543f3ce
The short version is something like this:
The calendar the Romans started with had been kind of been slapped together over the years, but it almost kind of made sense. They had months which mostly alternated between 30 and 31 days, and then an adjustable "intercalary" month to make up the difference. (Why they needed to have different lengths at all for the fixed months if they had that totally flexible intercalary thing is a question for the ages... as is the question of why they didn't add one more month so the intercalary would be more like 20 days instead of ~50.)
Also, somehow they had the length of the year wrong -- or hadn't noticed that their calendar didn't match it. Or something.
Then political maneuvering happened -- and the Roman Senate almost makes our Senate look sensible at times. They moved the intercalary so it was (get this) in the middle of another month. So you had the first part of February, then the intercalary, then the last 5 days of February. (I'm picturing Senator Julius Mansionus arguing that if the calendar made too much sense, the poor people of Rome would just use it to organize their schedules, and we can't have poor people being too organized because we all know what happens *then*.)
More to the point, though, they moved Januarius to the beginning of the year for basically political/superstitious reasons which also gave rise to a festival at the beginning of that month.
So now we have the following important events around the new year and the solstice: - The feast of Saturnalia (which had subsumed a lot of earlier solstice celebrations), starting mid-December and overlapping the solstice. - The birth of Mithras, which was right around the solstice - The festival of Janus, a week after Saturnalia, at the start of Januarius
It already would have been difficult to move things around at this point, since people liked Saturnalia overlapping the solstice and Mithras Day being on it and Janus's festival starting on the first of Januarius -- and moving Januarius back to be on the solstice would have meant that the solstice would be a week *after* both Saturnalia and Mithras Day, and the Feast of Janus would be *on* the solstice, and that would just be Wrong.
Then around 300 CE, the Christians started to get powerful and decided to make their guy's official birthday *just happen* to be on the same day as Mithras's, even though Biblical accounts put it almost certainly in April or so, because they wanted all the celebration to be about them instead of all these ancient traditions which they wanted to discourage. That kind of sealed the whole thing.
So basically, you can blame the War on Mithras.
Happy Saturnalia, everyone!