Ante-Nicene Fathers, Vol III:
Tertullian: Part II: On St. Philip's Conversation with Christ. He that Hath Seen Me, Hath Seen the Father. This Text Explained in an Anti-Praxean Sense.

Chapter XXIV.—On St. Philip’s Conversation with Christ. He that Hath Seen Me, Hath Seen the Father. This Text Explained in an Anti-Praxean Sense.

But there were some who even then did not understand. For Thomas, who was so long incredulous, said: “Lord, we know not whither Thou goest; and how can we know the way? Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me. If ye had known me, ye would have known the Father also:  but henceforth ye know Him, and have seen Him.” 8092 And now we come to Philip, who, roused with the expectation of seeing the Father, and not understanding in what sense he was to take “seeing the Father,” says:  “Show us the Father, and it sufficeth us.” 8093 Then the Lord answered him: “Have I been so long time with you, and yet hast thou not known me, Philip?” 8094 Now whom does He say that they ought to have known?—for this is the sole point of discussion. Was it as the Father that they ought to have known Him, or as the Son? If it was as the Father, Praxeas must tell us how Christ, who had been so long time with them, could have possibly ever been (I will not say understood, but even) supposed to have been the Father. He is clearly defined to us in all Scriptures—in the Old Testament as the Christ of God, in the New Testament as the Son of God.  In this character was He anciently predicted, in this was He also declared even by Christ Himself; nay, by the very Father also, who openly confesses Him from heaven as His Son, and as His Son glorifies Him. “This is my beloved Son;” “I have glorified Him, and I will glorify Him.” In this character, too, was He believed on by His disciples, and rejected by the Jews. It was, moreover, in this character that He wished to be accepted by them whenever He named the Father, and gave preference to the Father, and honoured the Father. This, then, being the case, it was not the Father whom, after His lengthened intercourse with them, they were ignorant of, but it was the Son; and accordingly the Lord, while upbraiding Philip for not knowing Himself who was the object of their ignorance, wished Himself to be acknowledged indeed as that Being whom He had reproached them for being ignorant of after so long a time—in a word, as the Son. And now it may be seen in what sense it was said, “He that hath seen me hath seen the Father,” 8095 —even in the same in which it was said in a previous passage, “I and my Father are one.” 8096 Wherefore?  Because “I came forth from the Father, and am come into the world” 8097 and, “I am the way: no man cometh unto the Father, but by me;” 8098 and, “No man can come to me, except the Father draw him;” 8099 and, “All things are delivered unto me by the Father;” 8100 and, “As the Father quickeneth (the dead), so also doth the Son;” 8101 and again, “If ye had known me, ye would have known the Father also.” 8102 For in all these passages He had shown Himself to be the Father’s Commissioner, 8103 through whose agency even the Father could be seen in His works, and heard in His words, and recognised in the Son’s administration of the Father’s words and deeds. The Father indeed was invisible, as Philip had learnt in the law, and ought at the moment to have remembered: “No man shall see God, and live.” 8104 So he is reproved for desiring to see the Father, as if He were a visible Being, and is taught that He only becomes visible in the Son from His mighty works, and not in the manifestation of His person. If, indeed, He meant the Father to be understood as the same with the Son, by saying, “He who seeth me seeth the Father,” how is it that He adds immediately afterwards, “Believest thou not that I am in the Father, and the Father in me?” 8105 He ought rather to have said: “Believest thou not that I am the Father?” With what view else did He so emphatically dwell on this point, if it were not to clear up that which He wished men to understand—namely, that He was the Son? And then, again, by saying, “Believest thou not that I am in the Father, and the Father in me,” 8106 He laid the greater stress on His question on this very account, that He should not, because He had said, “He that hath seen me, hath seen the Father,” be supposed to be the Father; because He had never wished Himself to be so regarded, having always professed Himself to be the Son, and to have come from the Father. And then He also set the conjunction of the two Persons in the clearest light, in order that no wish might be entertained of seeing the Father as if He were separately visible, and p. 621 that the Son might be regarded as the representative of the Father. And yet He omitted not to explain how the Father was in the Son and the Son in the Father. “The words,” says He, “which I speak unto you, are not mine,” 8107 because indeed they were the Father’s words; “but the Father that dwelleth in me, He doeth the works.” 8108 It is therefore by His mighty works, and by the words of His doctrine, that the Father who dwells in the Son makes Himself visible—even by those words and works whereby He abides in Him, and also by Him in whom He abides; the special properties of Both the Persons being apparent from this very circumstance, that He says, “I am in the Father, and the Father is in me.” 8109 Accordingly He adds: “Believe—”  What? That I am the Father? I do not find that it is so written, but rather, “that I am in the Father, and the Father in me; or else believe me for my works’ sake;” 8110 meaning those works by which the Father manifested Himself to be in the Son, not indeed to the sight of man, but to his intelligence.

Footnotes

John xiv. 5-7.

John 14.8.

John 14.9.

John xiv. 9.

John x. 30.

John xvi. 28.

John xiv. 6.

John vi. 44.

Matt. xi. 27.

John v. 21.

John xiv. 7.

Vicarium.

Ex. xxxiii. 20.

John xiv. 10.

John xiv. 11.

John xiv. 10.

John 14.10.

John 14.10.

John 14.11.