7.20.1
XX. Ὅ γε μὴν Διονύσιος πρὸς ταῖς δηλωθείσαις ἐπιστολαῖς αὐτοῦ ἔτι καὶ τὰς φερομένας ἑορταστικὰς τὸ τηνικαῦτα συντάττει, πανηγυρικωτέρους ἐν αὐταῖς περὶ τῆς τοῦ πάσχα ἑορτῆς ἀνακινῶν λόγους. τούτων τὴν μὲν Θλαυΐῳ προσφωνεῖ, τὴν δὲ Δομετίῳ καὶ Διδύμῳ, ἐν ἦ καὶ κανόνα ἐκτίθεται ὀκταετηρίδος, ὅτι μὴ ἄλλοτε ἢ μετὰ τὴν ἐαρινὴν ἰσημερίαν προσήκοι τὴν τοῦ πάσχα ἑορτὴν ἐπιτελεῖν, παριστάμενος· πρὸς ταύταις καὶ ὤην τοῖς κατ’ Ἀλεξάνδρειαν συμπρεσβυτέροις ἐπιστολὴν διαχαράττει ἑτέροις τε ὁμοῦ διαφόρως, καὶ ταύτας ἔτι τοῦ διωγμοῦ συνεστῶτος.
XX. But to resume. Dionysius, in addition to the letters of his that were mentioned, composed at that time also the festal letters which are still extant, in which he gives utterance to words specially suited to a solemn occasion with reference to the festival of the Pascha. Of these he addressed one to Flavius, another to Domitius and Didymus, in which also he sets forth a canon based on a cycle of eight years, proving that it is not proper to celebrate the festival of the Pascha at any other time than after the vernal equinox. In addition to these he penned also another letter to his fellow-presbyters at Alexandria, and others at the same time in different places. And these he wrote while the persecution was still proceeding.