...The second he [sc. King Numa] dedicated to the god Februus, who is believed to control rites of purification: the community had to be purified in that month, when he determined that the Good Gods be paid the offerings due them... Numa soon added one day to January, paying honor to the mystery of the odd number that nature revealed even before Pythagoras: as a result, both the year as a whole and the individual months (save February) had an odd number of days. (If all twelve months had either an odd or even number of days, their total would be an even number...)