Hilary of Poitiers De Syn., 61-64

61. A condemnation of that heresy on account of which the Synod was held necessarily concluded with an explanation of the whole faith that was being opposed. This heresy falsely stated that the beginning of the Son of God dated from His birth of Mary. According to evangelical and apostolic doctrine the cornerstone of our faith is that our Lord Jesus Christ, who is God and Son of God, cannot be separated from the Father in title or power or difference of substance or interval of time.

62. You perceive that the truth has been sought by many paths through the advice and opinions of different bishops, and the ground of their views has been set forth by the separate declarations inscribed in this creed. Every separate point of heretical assertion has been successfully refuted. The infinite and boundless God cannot be made comprehensible by a few words of human speech. Brevity often misleads both learner and teacher, and a concentrated discourse either causes a subject not to be understood, or spoils the meaning of an argument where a thing is hinted at, and is not proved by full demonstration. The bishops fully understood this, anti therefore have used for the purpose of teaching many definitions and a profusion of words that the ordinary understanding might find no difficulty, but that their hearers might be saturated with the truth thus differently expressed, and that in treating of divine things these adequate and manifold definitions might leave no room for danger or obscurity.

63. You must not be surprised, dear brethren, that so many creeds have recently been written. The frenzy of heretics makes it necessary. The danger of the Eastern Churches is so great that it is rare to find either priest or layman that belongs to this faith, of the orthodoxy of which you may judge. Certain individuals have acted so wrongly as to support the side of evil, and the strength of the wicked has been increased by the exile of some of the bishops, the cause of which you are acquainted with. I am not speaking about distant events or writing down incidents of which I know nothing: I have heard and seen the faults which we now have to combat. They are not laymen but bishops who are guilty. Except the bishop Eleusiusand his few comrades, the greater part of the ten provinces of Asia, in which I am now staying, really know not God. Would that they knew nothing about Him, for their ignorance would meet with a readier pardon than their detraction. These faithful bishops do not keep silence in their pain. They seek for the unity of that faith of which others have long since robbed them. The necessity of a united exposition of that faith was first felt when Hosius forgot his former deeds and words, and a fresh yet festering heresy broke out at Sirmium. Of Hosius I say nothing, I leave his conduct in the background lest man’s judgment should forget what once he was. But everywhere there are scandals, schisms and treacheries. Hence some of those who had formerly written one creed were compelled to sign another. I make no complaint against these long-suffering Eastern bishops, it was enough that they gave at least a compulsory assent to the faith after they had once been willing to blaspheme. I think it a subject of congratulation that a single penitent should be found among such obstinate, blaspheming and heretical bishops. But, brethren, you enjoy happiness and glory in the Lord, who meanwhile retain and conscientiously confess the whole apostolic faith, and have hitherto been ignorant of written creeds. You have not needed the letter, for you abounded in the spirit. You required not the office of a hand to write what you believed in your hearts and professed unto salvation. It was unnecessary for you to read as bishops what you held when new-born converts. But necessity has introduced the custom of ex-pounding creeds and signing expositions. Where the conscience is in danger we must use the letter. Nor is it wrong to write what it is wholesome to confess.

64. Kept always from guile by the gift of the Holy Spirit, we confess and write of our own will that there are not two Gods but one God; nor do we therefore deny that the Son of God is also God; for He is God of God. We deny that there are two incapable of birth, because God is one through the prerogative of being incapable of birth; nor does it follow that the Unbegotten is not God, for His source is the Unborn substance. There is not one subsistent Person, but a similar substance in both Persons. There is not one name of God applied to dissimilar natures, but a wholly similar essence belonging to one name and nature. One is not superior to the other on account of the kind of His substance, but one is subject to the other because born of the other. The Father is greater because He is Father, the Son is not the less because He is Son. The difference is one of the meaning of a name anti not of a nature. We confess that the Father is not affected by time, but do not deny that the Son is equally eternal. We assert that the Father is in the Son because the Son has nothing in Himself unlike the Father: we confess that the Son is in the Father because the existence of the Son is not from any other source. We recognize that their nature is mutual and similar because equal: we do not think them to be one Person because they are one: we declare that they are through the similarity of an identical nature one, in such a way that they nevertheless are not one Person.