De Synodis
8 For although it was necessary to reply to your letters, in which you offered me Christian communion with your faith, (and, moreover, certain of your number who were summoned to the Council which seemed pending in Bithynia did refuse with firm consistency of faith to hold communion with any but myself outside Gaul), it also seemed fit to use my episcopal office and authority, when heresy was so rife, in submitting to you by letter some godly and faithful counsel. For the word of God cannot be exiled as our bodies are, or so chained and bound that it cannot be imparted to you in any place. But when I had learned that synods were to meet in Ancyra and Ariminum, and that one or two bishops from each province in Gaul would assemble there, I thought it especially needful that I, who am confined in the East, should explain and make known to you the grounds of those mutual suspicious which exist between us and the Eastern bishops, though some of you know those grounds; in order that whereas you had condemned and they had anathematized this heresy that spreads from Sirmium, you might nevertheless know with what confession of faith the Eastern bishops had come to the same result that you had come to, and that I might prevent you, whom I hope to see as shining lights in future Councils, differing, through a mistake about words, even a hair's-breadth from pure Catholic belief, when your interpretation of the apostolic faith is identically the same and you are Catholics at heart.
9. Now it seems to me right and appropriate, before I begin my argument about suspicions and dissensions as to words, to give as complete an account as possible of the decisions of the Eastern bishops adverse to the heresy compiled at Sirmium. Others have published all these transactions very plainly, but much obscurity is caused by a translation from Greek into Latin, and to be absolutely literal is to be sometimes partly unintelligible.
10. You remember that in the Blasphemia, lately written at Sirmium, the object of the authors was to proclaim the Father to be the one and only God of all things, and deny the Son to be God: and while they determined that men should hold their peace about ὁμοούσιον and ὁμοιούσιον, they determined that God the Son should be asserted to be born not of God the Father, but of nothing, as the first creatures were, or of another essence than God, as the later creatures. And further that in saying the Father was greater in honour, dignity, splendour and majesty, they implied that the Son lacked those things which constitute the Father's superiority. Lastly, that while it is affirmed that His birth is unknowable, we were commanded by this Compulsory Ignorance Act not to know that He is of God: just as if it could be commanded or decreed that a man should know what in future he is to be ignorant of, or be ignorant of what he already knows. I have subjoined in full this pestilent and godless blasphemy, though against my will, to facilitate a more complete knowledge of the worth and reason of the replies made on the opposite side by those Easterns who endeavoured to counteract all the wiles of the heretics according to their understanding and comprehension.
A copy of the Blasphemia composed at Sirmium by Osius and Polamius.
11. Since there appeared to be some misunderstanding respecting the faith, all points have been carefully investigated and discussed at Sirmium in the presence of our most reverend brothers and fellow bishops, Valens, Ursacius and Germinius.
It is evident that there is one God, the Father Almighty, according as it is believed throughout the whole world; and His only Son Jesus Christ our Saviour, begotten of Him before the ages. But we cannot and ought not to say that there are two Gods, for the Lord Himself said, I will go unto My Father and your Father, unto My God and your God. So there is one God over all, as the Apostle has taught us, Is He God of the Jews only? Is He not also of the Gentiles? Yes, of the Gentiles also: seeing it is one God, which shall justify the circumcision by faith, and the uncircumcision through faith. And in all other things they agreed thereto, nor would they allow any difference.
But since some or many persons were disturbed by questions concerning substance, called in Greek οὐσία, that is, to make it understood more exactly, as to ὁμοούσιον, or what is called ὁμοιούσιον, there ought to be no mention made of these at all. Nor ought any exposition to be made of them for the reason and consideration that they are not contained in the divine Scriptures, and that they are above man's understanding, nor can any man declare the birth of the Son, of whom it is written, Who shall declare His generation ? For it is plain that only the Father knows how He begot the Son, and the Son how He was begotten of the Father. There is no question that the Father is greater. No one can doubt that the Father is greater than the Son in honour, dignity, splendour, majesty, and in the very name of Father, the Son Himself testifying, He that sent Me is greater than I. And no one is ignorant that it is Catholic doctrine that there are two Persons of Father and Son; and that the Father is greater, and that the Son is subordinated to the Father, together with all things which the Father has subordinated to Him, and that the Father has no beginning and is invisible, immortal and impassible, but that the Son has been begotten of the Father, God of God, Light of Light, and that the generation of this Son, as is aforesaid, no one knows but His Father. And that the Son of God Himself, our Lord and God, as we read, took flesh, that is, a body, that is, man of the womb of the Virgin Mary, of the Angel announced. And as all the Scriptures teach, and especially the doctor of the Gentiles himself, He took of Mary the Virgin, man, through whom He suffered. And the whole faith is summed up and secured in this, that the Trinity must always be preserved, as we read in the Gospel, Go ye and baptize all nations in the Name of the Father, and of the Son, and of the Holy Ghost. Complete and perfect is the number of the Trinity. How the Paraclete, the Spirit, is through the Son: Who was sent and came according to His promise in order to instruct, teach and sanctify the apostles and all believers.
12. After these many and most impious statements had been made, the Eastern bishops on their side again met together and composed definitions of their confession. Since, however, we have frequently to mention the words essence and substance, we must determine the meaning of essence, lest in discussing facts we prove ignorant of the signification of our words. Essence is a reality which is, or the reality of those things from which it is, and which subsists inasmuch as it is permanent. Now we can speak of the essence, or nature, or genus, or substance of anything. And the strict reason why the word essence is employed is because it is always. But this is identical with substance, because a thing which is, necessarily subsists in itself, and whatever thus subsists possesses unquestionably a permanent genus, nature or substance. When, therefore, we say that essence signifies nature, or genus, or substance, we mean the essence of that thing which permanently exists in the nature, genus, or substance. Now, therefore, let us review the definitions of faith drawn up by the Easterns.
I. “If any one hearing that the Son is the image of the invisible God, says that the image of God is the same as the invisible God, as though refusing to confess that He is truly Son: let him be anathema.”
13. Hereby is excluded the assertion of those who wish to represent the relationship of Father and Son as a matter of names, inasmuch as every image is similar in species to that of which it is an image. For no one is himself his own image, but it is necessary that the image should demonstrate him of whom it is an image. So an image is the figured and indistinguishable likeness of one thing equated with another. Therefore the Father is, and the Son is, because the Son is the image of the Father: and he who is an image, if he is to be truly an image, must have in himself his original's species, nature and essence in virtue of the fact that he is an image.
Source: On the Councils, or the Faith of the Easterns (New Advent)