The first day of January marks the beginning of the New Year according to both the modern Gregorian and Julian calendars. The month January was named after Janus, the god of beginnings and endings in ancient Rome, according to the Julian calendar. Nonetheless, in the Gregorian calendar, the first of January celebrates the birth of Jesus in a liturgy named the Feast of the Holy Name of Jesus, also known as the Feast of the Circumcision of Jesus.