Nicene and Post-Nicene Fathers, Ser. II, Vol. III:
The Ecclesiastical History, Dialogues, and Letters of Theodoret.: Festal.

XXV. Festal.

When the only begotten God had been made Man, and had wrought out our salvation, they who in those days saw Him from whom these bounties flowed kept no feast. But in our time, land and sea, town and hamlet, though they cannot see their benefactor with eyes of sense, keep a feast in memory of all He has done for them; and so great is the joy flowing from these celebrations that the streams of spiritual gladness run in all directions. Wherefore we now salute your piety, at once to signify the cheerfulness which the feast has caused in us, and to ask your prayers that we may keep it to the end.