By St. Symeon of Thessaloniki
(Responses to Various Questions, 104)
The fast of the Apostles was established in their honor, and rightly so for through them we have been deemed worthy of many good things, having been made manifest to us as practitioners and teachers of fasting and obedience, even unto death itself persevering in self-control. To this even the Latins bear witness unintentionally, honoring the Apostles on the days of their memorials with fasting; but we, in adhering to the Apostolic Constitutions compiled by Clement,* after the Descent of the Holy Spirit rejoice for one week and then, immediately after, we fast for a week, that we may not grow weak through soft living, as we are taught. At the same time we honor through fasting the Apostles who enjoined fasting.
Notes:
* "Therefore, after you have kept the festival of Pentecost, keep one week more festival, and after that fast; for it is reasonable to rejoice for the gift of God, and to fast after that relaxation period" (Apostolic Constitutions, Bk. 5, Ch. 20).
Translated by John Sanidopoulos.