De Synodis
II. “And if any one hearing the Son say, As the Father has life in Himself, so also has He given to the Son to have life in Himself, shall say that He who has received life from the Father, and who also declares, I live by the Father, is the same as He who gave life: let him be anathema.”
14. The person of the recipient and of the giver are distinguished so that the same should not be made one and sole. For since he is under anathema who has believed that, when recipient and giver are mentioned one solitary and unique person is implied, we may not suppose that the selfsame person who gave received from Himself. For He who lives and He through whom He lives are not identical, for one lives to Himself, the other declares that He lives through the Author of His life, and no one will declare that He who enjoys life and He through whom His life is caused are personally identical.
III. “And if any one hearing that the Only-begotten Son is like the invisible God, denies that the Son who is the image of the invisible God (whose image is understood to include essence) is Son in essence, as though denying His true Sonship: let him be anathema.”
15. It is here insisted that the nature is indistinguishable and entirely similar. For since He is the Only-begotten Son of God and the image of the invisible God, it is necessary that He should be of an essence similar in species and nature. Or what distinction can be made between Father and Son affecting their nature with its similar genus, when the Son subsisting through the nature begotten in Him is invested with the properties of the Father, viz., glory, worth, power, invisibility, essence? And while these prerogatives of divinity are equal we neither understand the one to be less because He is Son, nor the other to be greater because He is Father; since the Son is the image of the Father in species, and not dissimilar in genus; since the similarity of a Son begotten of the substance of His Father does not admit of any diversity of substance, and the Son and image of the invisible God embraces in Himself the whole form of His Father's divinity both in kind and in amount: and this is to be truly Son, to reflect the truth of the Father's form by the perfect likeness of the nature imaged in Himself.
IV. “And if any one hearing this text, For as the Father has life in Himself so also He has given to the Son to have life in Himself; denies that the Son is like the Father even in essence, though He testifies that it is even as He has said; let him be anathema. For it is plain that since the life which is understood to exist in the Father signifies substance, and the life of the Only-begotten which was begotten of the Father is also understood to mean substance or essence, He there signifies a likeness of essence to essence.”
16. With the Son's origin as thus stated is connected the perfect birth of the undivided nature. For what in each is life, that in each is signified by essence. And in the life which is begotten of life, i.e. in the essence which is born of essence, seeing that it is not born unlike (and that because life is of life), He keeps in Himself a nature wholly similar to His original, because there is no diversity in the likeness of the essence that is born and that begets, that is, of the life which is possessed and which has been given. For though God begot Him of Himself, in likeness to His own nature, He in whom is the unbegotten likeness did not relinquish the property of His natural substance. For He only has what He gave; and as possessing life He gave life to be possessed. And thus what is born of essence, as life of life, is essentially like itself, and the essence of Him who is begotten and of Him who begets admits no diversity or unlikeness.
V. “If any one hearing the words formed or created it and begot me spoken by the same lips, refuses to understand this begot me of likeness of essence, but says that begot me and formed me are the same: as if to deny that the perfect Son of God was here signified as Son under two different expressions, as Wisdom has given us to piously understand, and asserts that formed me and begot me only imply formation and not sonship: let him be anathema.”
17. Those who say that the Son of God is only a creature or formation are opposed on the fact that they say they have read The Lord formed or created me, which seems to imply formation or creation; but they omit the following sentence, which is the key to the first, and from the first wrest authority for their impious statement that the Son is a creature, because Wisdom has said that she was created. But if she were created, how could she be also born? For all birth, of whatever kind, attains its own nature from the nature that begets it: but creation takes its beginning from the power of the Creator, the Creator being able to form a creature from nothing. So Wisdom, who said that she was created, does in the next sentence say that she was also begotten, using the word creation of the act of the changeless nature of her Parent, which nature, unlike the manner and wont of human parturition, without any detriment or change of self created from itself what it begot. Similarly a Creator has no need of passion or intercourse or parturition. And that which is created out of nothing begins to exist at a definite moment. And He who creates makes His object through His mere power, and creation is the work of might, not the birth of a nature from a nature that besets it. But because the Son of God was not begotten after the manner of corporeal childbearing, but was born perfect God of perfect God; therefore Wisdom says that she was created, excluding in her manner of birth every kind of corporeal process.
18. Moreover, to show that she possesses a nature that was born and not created, Wisdom has added that she was begotten, that by declaring that she was created and also begotten, she might completely explain her birth. By speaking of creation she implies that the nature of the Father is changeless, and she also shows that the substance of her nature begotten of God the Father is genuine and real. And so her words about creation and generation have explained the perfection of her birth: the former that the Father is changeless, the latter the reality of her own nature. The two things combined become one, and that one is both in perfection: for the Son being born of God without any change in God, is so born of the Father as to be created; and the Father, who is changeless in Himself and the Son's Father by nature, so forms the Son as to beget Him. Therefore the heresy which has dared to aver that the Son of God is a creature is condemned because while the first statement shows the impossible perfection of the divinity, the second, which asserts His natural generation, crushes the impious opinion that He was created out of nothing.
VI. “And if any one grant the Son only a likeness of activity, but rob Him of the likeness of essence which is the corner-stone of our faith, in spite of the fact that the Son Himself reveals His essential likeness with the Father in the words, For as the Father has life in Himself, so also has He given to the Son to have life in Himself, as well as His likeness in activity by teaching us that What things soever the Father does, these also does the Son likewise, such a man robs himself of the knowledge of eternal life which is in the Father and the Son, and let him be anathema.”
Source: On the Councils, or the Faith of the Easterns (New Advent)