A well-known midrash explaining the universality of the Kalends festival beginning after the Winter Solstice attributes this psalm to Adam haRishon, the primordial Adam, as they describe being knitted together within the Earth in Psalms 139:13-16. In the Roman calendar, the calends or kalends (Latin: kalendae) is the first day of every month. Named after Janus, the Roman god of beginnings, and derived from ianua, “door,” January began with the first crescent moon after the winter solstice, marking the natural beginning of the year. Marcus Terentius Varro, in his Res Rusticae (37 BCE) divided the agricultural year into eight parts. In the final part beginning on the winter solstice, no hard work was to be done outdoors.