Nicene and Post-Nicene Fathers, Ser. II, Vol. III:
The Ecclesiastical History, Dialogues, and Letters of Theodoret.: The Epistle of the Emperor Constantine, concerning the matters transacted at the Council, addressed to those Bishops who were not present.

Chapter IX.—The Epistle of the Emperor Constantine, concerning the matters transacted at the Council, addressed to those Bishops who were not present.

The great emperor also wrote an account of the transactions of the council to those bishops who were unable to attend. And I consider it worth while to insert this epistle in my work, as it clearly evidences the piety of the writer.

“Constantinus Augustus to the Churches.

“Viewing the common public prosperity enjoyed at this moment, as the result of the great power of divine grace, I am desirous above all things that the blessed members of the Catholic Church should be preserved in one faith, in sincere love, and in one form of religion, towards Almighty God. But, since no firmer or more effective measure could be adopted to secure this end, than that of submitting everything relating to our most holy religion to the examination of all, or most of all, the bishops, I convened as many of them as possible, and took my seat among them as one of yourselves; for I would not deny that truth which is the source of my greatest joy, namely, that I am your fellow-servant. Every point obtained its due investigation, until the doctrine pleasing to the all-seeing God, and conducive to unity, was made clear, so that no room should remain for division or controversy concerning the faith.

“The commemoration of the most sacred paschal feast being then debated, it was unanimously decided, that it would be well that it should be everywhere celebrated upon the same day. What can be more fair, or more seemly, than that that festival by which we have received the hope of immortality should be carefully celebrated by all, on plain grounds, with the same order and exactitude? It was, in the first place, declared improper to follow the custom of the Jews in the celebration of this holy festival, because, their hands having been stained with crime, the minds of these wretched men are necessarily blinded. By rejecting their custom, we establish and hand down to succeeding ages one which is more reasonable, and which has been observed ever since the day of our Lord’s sufferings. Let us, then, have nothing in common with the Jews, who are our adversaries. For we have received from our Saviour another way. A better and more lawful line of conduct is inculcated by our holy religion. Let us with one accord walk therein, my much-honoured brethren, studiously avoiding all contact with that evil way. They boast that without their instructions we should be unable to commemorate the festival properly. This is the highest pitch of absurdity. For how can they entertain right views on any point who, after having compassed the death of the Lord, being out of their minds, are guided not by sound reason, but by an unrestrained passion, wherever their innate madness carries them. Hence it follows that they have so far lost sight of truth, wandering as far as possible p. 48 from the correct revisal, that they celebrate a second Passover in the same year. What motive can we have for following those who are thus confessedly unsound and in dire error? For we could never tolerate celebrating the Passover twice in one year. But even if all these facts did not exist, your own sagacity would prompt you to watch with diligence and with prayer, lest your pure minds should appear to share in the customs of a people so utterly depraved. It must also be borne in mind, that upon so important a point as the celebration of a feast of such sanctity, discord is wrong. One day has our Saviour set apart for a commemoration of our deliverance, namely, of His most holy Passion. One hath He wished His Catholic Church to be, whereof the members, though dispersed throughout the most various parts of the world, are yet nourished by one spirit, that is, by the divine will. Let your pious sagacity reflect how evil and improper it is, that days devoted by some to fasting, should be spent by others in convivial feasting; and that after the paschal feast, some are rejoicing in festivals and relaxations, while others give themselves up to the appointed fasts. That this impropriety should be rectified, and that all these diversities of commemoration should be resolved into one form, is the will of divine Providence, as I am convinced you will all perceive. Therefore, this irregularity must be corrected, in order that we may no more have any thing in common with those parricides and the murderers of our Lord. An orderly and excellent form of commemoration is observed in all the churches of the western, of the southern, and of the northern parts of the world, and by some of the eastern; this form being universally commended, I engaged that you would be ready to adopt it likewise, and thus gladly accept the rule unanimously adopted in the city of Rome, throughout Italy, in all Africa, in Egypt, the Spains, the Gauls, the Britains, Libya, Greece, in the dioceses of Asia, and of Pontus, and in Cilicia, taking into your consideration not only that the churches of the places above-mentioned are greater in point of number, but also that it is most pious that all should unanimously agree in that course which accurate reasoning seems to demand, and which has no single point in common with the perjury of the Jews.

“Briefly to summarize the whole of the preceding, the judgment of all is, that the holy Paschal feast should be held on one and the same day; for, in so holy a matter, it is not becoming that any difference of custom should exist, and it is better to follow the opinion which has not the least association with error and sin. This being the case, receive with gladness the heavenly gift and the plainly divine command; for all that is transacted in the holy councils of the bishops is to be referred to the Divine will. Therefore, when you have made known to all our beloved brethren the subject of this epistle, regard yourselves bound to accept what has gone before, and to arrange for the regular observance of this holy day, so that when, according to my long-cherished desire, I shall see you face to face, I may be able to celebrate with you this holy festival upon one and the same day; and may rejoice with you all in witnessing the cruelty of the devil destroyed by our efforts, through Divine grace, while our faith and peace and concord flourish throughout the world. May God preserve you, beloved brethren.”