Chapter XX.—The Festal Epistles of Dionysius, in which he also gives a Paschal Canon.
Dionysius, besides his epistles already mentioned, 2303 wrote at that time 2304 also his extant Festal Epistles, 2305 in which he uses words of panegyric respecting the passover feast. He addressed one of these to Flavius, 2306 and another to Domitius and Didymus, 2307 in which he sets forth a canon of eight years, 2308 maintaining that it is not proper to observe the paschal feast until after the vernal equinox. Besides these he sent another epistle to his fellow-presbyters in Alexandria, as well as various others to different persons while the persecution was still prevailing. 2309
Upon Dionysius of Alexandria, see Bk. VI. chap. 40, note 1, and see that note for references to the various passages in which Eusebius mentions or quotes from his epistles.305:2304
Eusebius supposes all of these epistles to have been written in the time of Valerian or Gallienus; but he is mistaken, at least so far as the epistle to Domitius and Didymus is concerned (see above, chap. 11, note 25), and possibly in regard to some of the others also.305:2305
τὰς φερομένας ἑορταστικ€ς. It was the custom for the bishops of Alexandria to write every year before Easter a sort of epistle, or homily, and in it to announce the time of the festival. These writings thus received the name Festal or Festival Epistles or Homilies (see Suicers Thesaurus s.v. ἑορταστικός, and Valesius note ad locum). This is apparently the earliest mention of such epistles. Others are referred to by Eusebius in chaps. 21 and 22, as written by Dionysius to various persons. Undoubtedly all the Alexandrian bishops during these centuries wrote such epistles, but none are extant, so far as I am aware, except a number by Athanasius (extant only in a Syriac version, published in Syriac and English by Cureton in 1846 and 1848), a few by Theophilus (extant only in Latin), and thirty by Cyril (published in Mignes Patr. Gr. LXXVII. 391 sq.).305:2306
Of this Flavius we know nothing. The epistle addressed to him is no longer extant.305:2307
On Domitius and Didymus, and the epistle addressed to them, see above, chap. 11, note 25. Eusebius quotes from the epistle in that chapter.305:2308
That is, an eight-year cycle for the purpose of determining the time of the full moon. Hippolytus had employed the old eight-year cycle, but had, as he thought, improved it by combining two in a single sixteen-year cycle (see above, Bk. VI. chap. 22), as was done also by the author of the so-called Cyprianic Chronicle at the middle of the third century. The more accurate nineteen-year Metonic cycle (already in use among the Greeks in the fifth century b.c.) had not come into general use in the Church until later than this time. The Nicene Council sanctioned it and gave it wide currency, but it had apparently not yet come into use in the Church. In fact, the first Christian to make use of it for the computation of Easter, so far as we know, was Anatolius of Alexandria, later bishop of Laodicea (see below, chap. 32, §14). It was soon adopted in the Alexandrian church, and already in the time of Athanasius had become the basis of all Easter calculations, as we can gather from Athanasius Festal Epistles. From about the time of the Nicene Council on, Alexandria was commonly looked to for the reckoning of the date of Easter, and although an older and less accurate cycle remained in use in the West for a long time, the nineteen-year cycle gradually won its way everywhere. See Idelers great work on chronology, and cf. Hefeles Conciliengesch. 2d ed. 1. p. 332, and Lightfoot in the Dict. of Christ. Biog. II. p. 313 sq.305:2309
These various epistles are no longer extant, nor do we know the names of the persons to whom they were addressed. At least a part of them, if not all, were very likely written during the Valerian persecution, as Eusebius states, for the fact that he made a mistake in connection with the epistle to Domitius and Didymus does not prove that he was in error in regard to all the others as well.