October (Roman month) did not number days of a month sequentially from the 1st through the last day. Instead, they counted back from the three fixed points of the month: the Nones (5th or 7th), the Ides (13th or 15th), and the Kalends (1st) of the following month. The Nones of October was the 7th, and the Ides was the 15th. The last day of October was the "pridie Kalendas Novembris," "day before the Kalends of November". Roman counting was inclusive; October 9 was "ante diem VII Idūs Octobris", "the 7th day before the Ides of October," usually abbreviated "a.d. VII Id. Oct."
September (Roman month) the Republican era, and in the earliest period, the consuls took office on the Ides of September. The month was often represented in art by the grape harvest. September was the birth month of no fewer than four major Roman emperors, including Augustus. The emperor Commodus renamed the month after either himself or Hercules—an innovation that was repealed after his murder in 192. In the Eastern provinces of the Roman Empire, the year began with September on some calendars, and was the beginning of the imperial tax year. For the month of September, ancient farmers' almanacs "(menologia rustica)" take note