De Synodis 109

IX. "And if any one, because the Father is never admitted to be the Son and the Son is never admitted to be the Father, when he says that the Son is other than the Father (because the Father is one Person and the Son another, inasmuch as it is said, There is another that beareth witness of Me, even the father who sent Me), does in anxiety for the distinct personal qualities of the Father and the Son which in the Church must be piously understood to exist, fear that the Son and the Father may sometimes be admitted to be the same Person, and therefore denies that the Son is like in essence to the Father: let him be anathema." 23. It was said unto the apostles of the Lord, Be ye wise as serpents, and harmless as doves. Christ therefore wished there to be in us the nature of different creatures: but in such a sort that the harmlessness of the dove might temper the serpent's wisdom, and the wisdom of the serpent might instruct the harmlessness of the dove, and that so wisdom might be made harmless and harmlessness wise. This precept has been observed in the exposition of this creed. For the former sentence of which we have spoken guarded against the teaching of a unity of person under the cloak of an essential likeness, and against the denial of the Son's birth as the result of an identity of nature, lest we should understand God to be a single monad because one Person does not differ in kind from the other. In the next sentence, by harmless and apostolic wisdom we have again taken refuge in that wisdom of the serpent to which we are bidden to be conformed no less than to the harmlessness of the dove, lest perchance through a repudiation of the unity of persons on the ground that the Father is one Person and the Son another, a preaching of the dissimilarity of their natures should again take us unawares, and lest on the ground that He who sent and He who was sent are two Persons (for the Sent and the Sender cannot be one Person) they should be considered to have divided and dissimilar natures, though He who is born and He who begets Him cannot be of a different essence. So we preserve in Father and in Son the likeness of an identical nature through an essential birth: yet the similarity of nature does not injure personality by making the Sent and the Sender to be but one. Nor do we do away with the similarity of nature by admitting distinct personal qualities, for it is impossible that the one God should be called Son and Father to Himself. So then the truth as to the birth supports the similarity of essence and the similarity of essence does not undermine the personal reality of the birth. Nor again does a profession of belief in the Begetter and the Begotten exclude a similarity of essence; for while the Begetter and the Begotten cannot be one Person, He who is born and He who begets cannot be of a different nature.