Epiphany (holiday) the calendar used, calling the feast that of the Nativity and Theophany of Our Lord. Origen's list of festivals (in "Contra Celsum", VIII, xxii) omits any reference to Epiphany. The first reference to an ecclesiastical feast of the Epiphany, in Ammianus Marcellinus (XXI:ii), is in 361. In parts of the Eastern Church, January 6 continued for some time as a composite feast that included the Nativity of Jesus: though Constantinople adopted December 25 to commemorate Jesus' birth in the fourth century, in other parts the Nativity of Jesus continued to be celebrated on January 6, a date later devoted exclusively
Epiphany (holiday) the Sunday occurring after 6 January". Before the 1969 revision of its liturgy, the Sundays following the Octave of Epiphany or, when this was abolished, following the Feast of the Baptism of the Lord, which was instituted to take the place of the Octave Day of Epiphany were named as the "Second (etc., up to Sixth) Sunday after Epiphany", as the at least 24 Sundays following Pentecost Sunday and Trinity Sunday were known as the "Second (etc.) Sunday after Pentecost". (If a year had more than 24 Sundays after Pentecost, up to four unused post-Epiphany Sundays were inserted between the