6 We do not deny that all the sayings which are preserved of His, refer to His nature. But, if Jesus Christ be man and God, neither God for the first time, when He became man, nor then ceasing to be God, nor after He became Man in God less than perfect man and perfect God, then the mystery of His words must be one and the same with that of His nature. When according to the time indicated, we disconnect His divinity from humanity, then let us also disconnect His language as God from the language of man; when we confess Him God and man at the same time, let us distinguish at the same time His words as God and His words as man; when after His manhood and Godhead, we recognise again the time when His whole manhood is wholly God, let us refer to that time all that is revealed concerning it. It is one thing, that He was God before He was man, another, that He was man and God, and another, that after being man and God, He was perfect man and perfect God.
Do not then confuse the times and natures in the mystery of the dispensation, for according to the attributes of His different natures, He must speak of Himself in relation to the mystery of His humanity, in one way before His birth, in another while He was yet to die, and in another as eternal.
Source: On the Trinity (New Advent)