In the first article of this series, I wrote about the quest for a good calendar, and I mentioned the Babylonian version: a cycle of nineteen years, in which the third, sixth, eighth, eleventh, fourteenth, seventeenth, and last year get an additional, thirteenth month. In other words, it is a cycle of 19×12 + 7 = 235 months, which are indeed – give or take a few hours – identical to nineteen years. New Year’s day will always be the New Moon closest to the beginning of the spring.
Because the Babylonian cycle, which is also known as the Cycle of Meton, is nearly faultless, it was adapted by several other nations, including the Jews. The document known as Some Works of the Law, which is probably a letter to the high priest Jonathan (r.150–143 BC), seems to be a response to the adoption of a foreign calendar: the author tries to persuade the addressee that there are better calendars. The high priest was not convinced, however, and the Jews use the Babylonian calendar until this very day.