This is the year that Julius Ceasar prepared for the introduction of his calendar reform, which offically began the following year. The extra days were added to 46 BC so the Julian Calendar could begin on a day that would ensure its conformity to the divisions of the solar year: mainly, the spring equinox.

But it is curious that we report, as a historical fact, that some period of time we call a "year" was 445 days long. Imagine how odd it would be to say that the noon-hour on a certain day lasted 90 minutes!

In reporting that 46 BC was 445 days long, we seem to acknowledge that historical years are not necessarily defined by our present conventions. We do not follow our own, Gregorian calendar and insist that 46 BC could only have been 365 days long, since that's how long years are--if they're not leap years.

Rather, our conception of historical time-periods like years seems to defer to the people who lived in those periods. The year in which they lived is to be defined the way they defined it. Yet, on the other hand, we don't defer totally to their conception of time, since they surely didn't designate that year as 46 BC.

A similar curiosity attends the odd months of Gregorian Reform. It is regularly reported that October 1582 was 10 days short: the 4th was followed immediately by the 15th. Similarly, September 1752 was 11 days short in Britian.

But notice this: Neither the earlier, Julian calendar, nor the later, Gregorian calendar, defines the month of October 1582 as having only 21 days. October always has 31 days in each calendar. (Try this on-line experiment.)

So when we say October had only 21 days in 1582, we must again be deferring to some definition or designation of the people who lived in that period of time. Yet if these people didn't follow either the Julian or Gregorian calendars in that year of the short October, then what calendar did they follow?

Suppose we say that the people in 1582 followed a unique calendar all their own: one with a short October. This suggestion emphasizes the idea that historical time is to be defined and designated by the people who lived in it. But in that case, we'll have to stop saying that the Gregorian calendar began in 1582. If we say no one followed the Gregorian calender in 1582, this means it can only have been instituted in 1583.

On the other hand, we could say that the people in 1582 followed the Julian calendar for part of that year, and then followed the Gregorian calendar for the rest of the year. But when we say this, what do we mean by the "year" that was partly Julian and partly Gregorian? It couldn't have been either a Julian or a Gregorian year, since it had only 355 days. So what kind of "year" was 1582? (Answer: "A year of confusion.")

All this confusion may be avoided if we stop deferring to the experience of historical people in defining and designating past time-periods. We can say that 1582 was exactly 365 days long, just like any other common year on the Gregorian calendar. When we place the Gregorian reform in 1582, we designate that time as the year historical people started keeping time the way we do--the correct way, as far as we're concerned.

This means, too, that "Retroactive Reform" must be possible.

Calendar Experiment:

Follow this link to a calendar program, and enter 10 1582 in the field to see what October 1582 looked like according to the Gregorian Calendar.

See also The Julian and Gregorian Proleptic Calendars.

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