Ianuarius

Mensis Ianuarius or Januarius ("January") is the first month of the ancient Roman calendar, from which the English name of the month derives. It was followed by Februarius ("February"). In the calendars of the Roman Republic, Ianuarius had 29 days. Two days were added when the calendar was reformed under Julius Caesar in 45 BC.

In the oldest Roman calendar, which the Romans believed to have been instituted by their legendary founder Romulus, the first month was Martius ("Mars' month", March), and the calendar year had only ten months. Ianuarius and Februarius were supposed to have been added by Numa Pompilius, the second king of Rome, originally at the end of the year. It is unclear when the Romans reset the course of the year so that January and February came first.Ianuarius is conventionally thought to have taken its name from Janus, the dual-faced god of beginnings, openings, passages, gates and doorways, but according to ancient Roman farmers' almanacs Juno was the tutelary deity of the month.

Many Roman festivals and religious observances reflect the Romans' agrarian way of life in their early history. Agricultural calendars (menologia rustica) show that for farmers, January continued the relatively slack time they experienced in December. For January, these almanacs advised farmers to expect 9¾ hours of daylight and 14¼ hours of darkness, and to sharpen stakes, cut willows and reeds, and offer sacrifice to the Dei Penates, tutelary deities. The agricultural writer Columella says that farmers who were religiosiores, more scrupulous than others, would refrain from working the land until January 13, except that on January 1 they should make an auspicious gesture (auspiciandi causa) of beginning work on everything they wanted to get done that year.

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