De Synodis
And in one our Lord Jesus Christ, the Son of God, born of the Father, Only-begotten, that is, of the substance of the Father, God of God, Light of Light, Very God of very God, born not made, of one substance with the Father (which in Greek they call ὁμοοίσιον); By whom all things were made which are in heaven and in earth, Who for our salvation came down, And was incarnate, And was made man, And suffered, And rose again the third day, And ascended into heaven, And shall come to judge the quick and the dead.
And in the Holy Ghost.
“But those who say, There was when He was not, And before He was born He was not, And that He was made of things that existed not, or of another substance and essence, saying that God was able to change and alter, to these the Catholic Church says anathema.”
Here the Holy Council of religious men introduces no prior substance divided between two Persons, but the Son born of the substance of the Father. Do we, too, deny or confess anything else? And after other explanations of our common faith, it says, Born not made, of one substance with the Father (which in Greek they call ὁμοούσιον). What occasion is there here for an erroneous interpretation? The Son is declared to be born of the substance of the Father, not made: lest while the word born implies His divinity, the word made should imply He is a creature. For the same reason we have of one substance, not to teach that there is one solitary divine Person, but that the Son is born of the substance of God and subsists from no other source, nor in any diversity caused by a difference of substance. Surely again this is our faith, that He subsists from no other source, and He is not unlike the Father. Is not the meaning here of the word ὁμοούσιον that the Son is produced of the Father's nature, the essence of the Son having no other origin, and that both, therefore, have one unvarying essence? As the Son's essence has no other origin, we may rightly believe that both are of one essence, since the Son could be born with no substance but that derived from the Father's nature which was its source.
85. But perhaps on the opposite side it will be said that it ought to meet with disapproval, because an erroneous interpretation is generally put upon it. If such is our fear, we ought to erase the words of the Apostle, There is one Mediator between God and men, the man Christ Jesus, because Photinus uses this to support his heresy, and refuse to read it because he interprets it mischievously. And the fire or the sponge should annihilate the Epistle to the Philippians, lest Marcion should read again in it, And was found in fashion as a man, and say Christ's body was only a phantasm and not a body. Away with the Gospel of John, lest Sabellius learn from it, I and the Father are one. Nor must those who now affirm the Son to be a creature find it written, The Father is greater than I. Nor must those who wish to declare that the Son is unlike the Father read: But of that day and hour knows no man, no, not the angels which are in heaven, neither the Son, but the Father. We must dispense, too, with the books of Moses, lest the darkness be thought coeval with God who dwells in the unborn light, since in Genesis the day began to be after the night; lest the years of Methuselah extend later than the date of the deluge, and consequently more than eight souls were saved; lest God hearing the cry of Sodom when the measure of its sins was full should come down as though ignorant of the cry to see if the measure of its sins was full according to the cry, and be found to be ignorant of what He knew; lest any one of those who buried Moses should have known his sepulchre when he was buried; lest these passages, as the heretics think, should prove that the contradictions of the law make it its own enemy. So as they do not understand them, we ought not to read them. And though I should not have said it myself unless forced by the argument, we must, if it seems fit, abolish all the divine and holy Gospels with their message of our salvation, lest their statements be found inconsistent; lest we should read that the Lord who was to send the Holy Spirit was Himself born of the Holy Spirit; lest He who was to threaten death by the sword to those who should take the sword, should before His passion command that a sword should be brought; lest He who was about to descend into hell should say that He would be in paradise with the thief; lest finally the Apostles should be found at fault, in that when commanded to baptize in the name of the Father, and the Son, and the Holy Ghost, they baptized in the name of Jesus only. I speak to you, brethren, to you, who are no longer nourished with milk, but with meat, and are strong. Shall we, because the wise men of the world have not understood these things, and they are foolish unto them, be wise as the world is wise and believe these things foolish? Because they are hidden from the godless, shall we refuse to shine with the truth of a doctrine which we understand? We prejudice the cause of divine doctrines when we think that they ought not to exist, because some do not regard them as holy. If so, we must not glory in the cross of Christ, because it is a stumbling-block to the world; and we must not preach death in connection with the living God, lest the godless argue that God is dead.
86. Some misunderstand ὁμοούσιον; does that prevent me from understanding it? The Samosatene was wrong in using the word ὁμοούσιον; does that make the Arians right in denying it? Eighty bishops once rejected it; but three hundred and eighteen recently accepted it. And for my own part I think the number sacred, for with such a number Abraham overcame the wicked kings, and was blessed by Him who is a type of the eternal priesthood. The former disapproved of it to oppose a heretic: the latter surely approved of it to oppose a heretic. The authority of the fathers is weighty, is the sanctity of their successors trivial? If their opinions were contradictory, we ought to decide which is the better: but if both their approval and disapproval established the same fact, why do we carp at such good decisions?
87. But perhaps you will reply, 'Some of those who were then present at Nicæa have now decreed that we ought to keep silence about the word ὁμοούσιον.' Against my will I must answer: Do not the very same men rule that we must keep silence about the word ὁμοιούσιον? I beseech you that there may be found no one of them but Hosius, that old man who loves a peaceful grave too well, who shall be found to think that we ought to keep silence about both. Amid the fury of the heretics into what straits shall we fall at last, if while we do not accept both, we keep neither? For there seems to be no impiety in saying that since neither is found in Scripture, we ought to confess neither or both.
Source: On the Councils, or the Faith of the Easterns (New Advent)