 These different periods amounted in all to three, five, ten, twelve or fifteen years, according to the gravity of the sins.This discipline, which was rapidly mitigated, ceased to be observed by the close of the fourth century.The relative penitential canons are contained in the canonical letter of St. Gregory Thaumaturgus (about 263; P. G., X, 1019), the Councils of Ancyra (314), Neocaesarea (314-20), Nicaea (325), and the three canonical letters of St.