John 14:7

(vii. de Trin) Or thus: When it is said that the Son is the way to the Father, is it meant that He is so by His teaching, or by His nature? We shall be able to see from what follows: If ye had known Me, ye should have known My Father also. In His incarnation asserting His Divinity, He maintained a certain order of sight and knowledge: separating the time of seeing from that of knowing. For Him, who He saith must be known, He speaks of as already seen: that henceforward they might from this revelation have knowledge of the Divine Nature which they had all along seen in Him.

(Hom. lxxiii. 2) If ye had known Me, He says, ye should have known My Father also; i. e. If ye had known My substance and dignity, ye would have known the Father's. They did know Him, but not as they ought to do. Nor was it till afterwards, when the Spirit came, that they were fully enlightened. On this account He adds, And from henceforth ye know Him, know Him, that is, spiritually. And have seen Him, i. e. by Me; meaning that he who had seen Him, had seen the Father. They saw Him, however, not in His pure substance, but clothed in flesh.

Connecting, therefore, His previous words with those that follow, He proceeded to say, "If ye had known me, ye should certainly have known my Father also." This conforms to His previous words, "No man cometh unto the Father but by me." And then He adds: "And from henceforth ye know Him, and have seen Him." But Philip, one of the apostles, not understanding what he had just heard, said, "Lord, show us the Father, and it sufficeth us." And the Lord replied to him, "Have I been so long time with you, and yet have ye not known me, Philip? he that seeth me, seeth also the Father." Already, therefore, they knew the Son, if not all of them, those at least to whom it is said, "And whither I go ye know, and the way ye know;" for He is Himself the way. But they knew not the Father, and so have also to hear, "If ye have known me, ye have known my Father also;" that is, through me ye have known Him also. For I am one, and He another. But that they might not think Him unlike, He adds, "And from henceforth ye know Him, and have seen Him." For they saw His perfectly resembling Son, but needed to have the truth impressed on them, that exactly such as was the Son whom they saw, was the Father also whom they did not see. And to this points what is afterwards said to Philip, "He that seeth me, seeth also the Father." Not that He Himself was Father and Son, which is a notion of the Sabellians, who are also called Patripassians, condemned by the Catholic faith; but that Father and Son are so alike, that he who knoweth one knoweth both. For we are accustomed to speak in this way of two who closely resemble each other, to those who are in the habit of seeing one of them, and wish to know what like the other is, so that we say, In seeing the one, you have seen the other. In this way, then, is it said "He that seeth me, seeth also the Father." Not, certainly, that He who is the Son is also the Father, but that the Son in no respect disagrees with the likeness of the Father. For had not the Father and Son been two persons, it would not have been said, "If ye have known me, ye have known my Father also." Such is certainly the case; for "no one," He says, "cometh unto the Father but by me: if ye have known me, ye have known my Father also;" because it is I, who am the only way to the Father, that will lead you to Him, that He also may Himself become known to you. But as I am in all respects His perfect image, "from henceforth ye know Him" in knowing me; "and have seen Him," if you have seen me with the spiritual eyesight of the soul.

How can our Lord say, If ye had known Me, ye should have known My Father also; when He has just said, Whither I go ye know, and the way ye know? We must suppose that some of them knew, and others not: among the latter, Thomas.