Februarius, fully Mensis Februarius ("month of Februa"), was the shortest month of the Roman calendar from which the Julian and Gregorian month of February derived. It was eventually placed second in order, preceded by Ianuarius ("month of Janus", January) and followed by Martius ("month of Mars", March). In the oldest Roman calendar, which the Romans believed to have been instituted by their legendary founder Romulus, March was the first month, and the calendar year had only ten months in all. 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. Februarius was the only month in the pre-Julian calendar to have an even number of days, numbering 28. This was mathematically necessary to permit the year itself to have an odd number of days. Ancient sources derived Februarius from februum, a thing used for ritual purification. Most of the observances in this month concerned the dead or closure, reflecting the month's original position at the end of the year. The Parentalia was a nine-day festival honoring the ancestors and propitiating the dead, while the Terminalia was a set of rituals pertaining to boundary stones that was probably also felt to reinforce the boundary of the year. In the agricultural year Many Roman festivals and religious observances reflect the Romans' agrarian way of life in their early history. In his treatise on farming, Varro divides the agricultural year into eight phases, with Spring beginning officially on February 7, when Favonius the west wind was thought to start blowing favorably and it was time to ready the fields. The grain fields were to be weeded, vineyards tended, and old reeds burned. Some kinds of trees were pruned, and attention was given to olive and fruit trees. The agricultural writer Columella says that meadows and grain fields are "purged" (purguntur), probably both in the practical sense of clearing away old debris and by means of ritual. The duties of February thus suggest the close bond between agriculture and religion in Roman culture. According to the farmers' almanacs, the tutelary deity of the month was Neptune. Dates The Romans did not number days of a month sequentially from the 1st through the last day. Instead, they counted back from the three