John 17:8

But what human language will suffice to explain how the Father gave those words to the Son? The question, of course, will appear easier if we suppose Him to have received such words in His capacity as the Son of man. And yet, although thus born of the Virgin, who will undertake to relate when and how it was that He learned them, since even that very generation which He had of the Virgin who will venture to declare? But if our idea be that He received these words of the Father in His capacity as begotten of, and co-eternal with, the Father, let us then exclude all such thoughts of time as if He existed previous to His possessing them, and so received the possession of that which He had not before; for whatever God the Father gave to God the Son, He gave in the act of begetting. For the Father gave those things to the Son without which He could not be the Son, in the same manner as He gave Him being itself. For how otherwise would He give any words to the Word, wherein in an ineffable way He hath spoken all things?

"And they have kept Thy word." "Now they have known that all things whatsoever Thou hast given Me are of Thee." How did they "keep Thy word"? "By believing in Me, and giving no heed to the Jews. For he that believeth in Him, it saith, 'hath set to his seal that God is true.'" (c. iii. 33.) Some read, "Now I know that all things whatsoever Thou hast given Me are of Thee." But this would have no reason; for how would the Son be ignorant of the things of the Father? No the words are spoken of the disciples. "From the time," He saith, "that I told them these things, they have learnt that all that Thou hast given Me is from Thee; nothing is alien, nothing peculiar to Me, with Thee." "They therefore have known that all things, whatsoever I teach, are Thy doctrines and teachings." "And whence have they learnt it?" From My words; for so have I taught them. And not only this have I taught them, but also that "I came out from Thee." For this He was anxious to prove through all the Gospel.

He proceeds to say, "And they have kept Thy word: now they have known that all things, whatsoever Thou hast given me, are of Thee;" that is, they have known that I am of Thee. For the Father gave all things at the very time when He begat Him who was to have all things. "For I have given unto them," He says, "the words which Thou gavest me; and they have received them;" that is, they have understood and kept hold of them. For the word is received when it is perceived by the mind. "And they have known truly," He adds, "that I came out from Thee, and they have believed that Thou didst send me." In this last clause we must also supply "truly;" for when He said, "They have known truly," He intended its explanation by adding, "and they have believed." That, therefore, "they have believed truly" which "they have known truly;" just as "I came out from Thee" is the same as "Thou didst send me." When, therefore, He said, "They have known truly," lest any might suppose that such a knowledge was already acquired by sight, and not by faith, He subjoined the explanation, "And they have believed," so that we should supply "truly," and understand the saying, "They have known truly," as equivalent to "They have believed truly:" not in the way which He intimated shortly before, when He said, "Do ye now believe? The hour cometh, and is now come, that ye shall be scattered, every man to his own, and shall leave me alone." But "they have believed truly," that is, in the way it ought to be believed, without constraint, with firmness, constancy, and fortitude: no longer now to go to their own, and leave Christ alone. As yet, indeed, the disciples were not of the character He here describes in words of the past tense, as if they were so already, but as thereby declaring beforehand what sort they were yet to be, namely, when they had received the Holy Spirit, who, according to the promise, should teach them all things. For how was it, before they received the Spirit, that they kept that word of His which He spake regarding them, as if they had done so, when the chief of them thrice denied Him, after hearing from His lips the future fate of the man who denied Him before men? He had given them, therefore, as He said, the words which the Father gave Him; but when at length they received them spiritually, not in an outward way with their ears, but inwardly in their hearts, then they truly received them, for then they truly knew them; and they truly knew them, because they truly believed.