It is unclear how the biblical calendar was set, despite the fact that the observance of many biblical laws, such as the holiday celebrations, is dependent upon calendrical calculation. In the immediate postbiblical period, at the end of the Second Temple, there were competing calendrical systems, and it is unclear which one was predominant. The best-known of these calendars was the Pharisaic luni-solar system, which eventually became the accepted rabbinic calendar. The months of this calendar were lunar, beginning with the new moon. The years, however, f…