February’s Labor of the Month: Survival

The Medieval Year: Sixteenth Day before the Kalends of March

Good morrow, Benedick. Why, what’s the matter,
That you have such a February face,
So full of frost, of storm and cloudiness?
—Much Ado about Nothing

Have you ever wondered why we use the term “leap year” to denote the years that have, thanks to Julius Caesar, one extra day in February? If we’re comparing calendrical durations to jumps, one day seems more like a tiny hop than a leap, and in any case, why speak of a jump at all? The name would make more sense for the other three years in the four-year cycle, since these are the years when we “jump over” February 29th by going directly from February 28th to March 1st.

Well, it turns out that the logic of a “leap year” may have roots in medieval spirituality. The term dates back to the fourteenth century and probably derives, according to the Oxford Dictionary of Word Origins, from

the fact that in a leap year feast days after February fall two days of the week later than in the previous year, rather than the usual one day, and could be said to have “leaped” a day.

Caesar devised the leap-year scheme with the help of the Greek Astronomer Sosigenes, and let’s give credit where it’s due: living in the first century BC, and thus totally lacking advanced technology, they decided that the length of a year was 365.25 days. The actual length, according to modern scientists armed to the teeth with telescopes, computers, satellites, etc., is 365.24219 days. That’s a difference of 0.00781 days, or about 11.25 minutes per year.