The Feast of Sts. Basil the Great and Gregory Nazianzen, Bishops and Doctors of the Church
is today. There is information on them here and here.

Basil and Gregory were both natives of Cappadocia, but here, again, under different circumstances; Basil was born of a good family, and with Christian ancestors; Gregory was the son of the bishop of Nazianzus, who had been brought up an idolater, or rather an Hypsistarian, a mongrel sort of religionist, part Jew, part Pagan. He was brought over to Christianity by the efforts of his wife Nonna, and at Nazianzus admitted by baptism into the Church. In process of time he was made bishop of that city; but not having a very firm hold of the faith, he was betrayed in 360 into signing the Ariminian creed, which caused him much trouble, and from which at length his son recovered him. Cæsarea being at no unsurmountable distance from Nazianzus, the two friends had known each other in their own country; but their intimacy began at Athens, whither they separately repaired for the purposes of education. This was about A.D. 350, when each of them was twenty-one years of age. Gregory came to the seat of learning shortly before Basil, and thus was able to be his host and guide on his arrival; but fame had reported Basil's merits before he came, and he seems to have made his way, in a place of all others most difficult to a stranger, with a facility peculiar to himself. He soon found himself admired and respected by his fellow-students; but Gregory was his only friend, and shared with him the reputation of talents and attainments.

Venerable John Henry Newman, Historical Sketches Volume II.