Feast of St. Basil and St. Gregory

Today is the feast day of both St. Basil the Great and St. Gregory of Nyssa, who were brothers. They are as 4th century saints quite late compared to most of those whose feast days fall in the 12 days of Christmas (although Thomas Beckett is even quite a bit later); their role was in resisting the Arian heresy and developing the theology by which the exact nature of the relationship of Father, Son, and Holy Spirit is understood.