John 6:62

"Then what if ye shall see the Son of man ascending where He was before?" What is this? Did He hereby solve the question that perplexed them? Did He hereby uncover the source of their offense? He did clearly, if only they understood. For they supposed that He was going to deal out His body to them; but He said that He was to ascend into heaven, of course, whole: "When ye shall see the Son of man ascending where He was before;" certainly then, at least, you will see that not in the manner you suppose does He dispense His body; certainly then, at least, you will understand that His grace is not consumed by tooth-biting. And He said, "It is the Spirit that quickeneth; the flesh profiteth nothing." Before we expound this, as the Lord grants us, that other must not be negligently passed over, where He says, "Then what if ye shall see the Son of man ascending where He was before?" For Christ is the Son of man, of the Virgin Mary. Therefore Son of man He began to be here on earth, where He took flesh from the earth. For which cause it was said prophetically, "Truth is sprung from the earth." Then what does He mean when He says, "When ye shall see the Son of man ascending where He was before"? For there had been no question if He had spoken thus: "If ye shall see the Son of God ascending where He was before." But since He said, "The Son of man ascending where He was before," surely the Son of man was not in heaven before the time when He began to have a being on earth? Here, indeed, He said, "where He was before," just as if He were not there at this time when He spoke these words. But in another place He says, "No man has ascended into heaven but He that came down from heaven, the Son of man who is in heaven." He said not "was," but, saith He, "the Son of man who is in heaven." He was speaking on earth, and He declared Himself to be in heaven. […]

Or, these words are an answer to their mistake. They supposed that He was going to distribute His body in bits: whereas He tells them now, that He should ascend to heaven whole and entire: What and if ye shall see the Son of man ascend up where He was before? ye will then see that He does not distribute His body in the way ye think. Again; Christ became the Son of man, of the Virgin Mary here upon earth, and took flesh upon Him: He says then, What and if ye shall see the Son of man ascend up where He was before? to let us know that Christ, God and man, is one person, not two; and the object of one faith, not a quaternity, but a Trinity. He was the Son of man in heaven, as He was Son of God upon earth; the Son of God upon earth by assumption of the flesh, the Son of man in heaven, by the unity of the person.

"When Jesus knew in Himself that His disciples murmured at it," (for this is an attribute of His Godhead to bring secret things to light,) "He said unto them, Doth this offend you? What and if ye shall see the Son of Man ascend up where He was before?" This also He doth in the case of Nathanael, saying, "Because I said unto thee, I saw thee under the fig-tree, believest thou? Thou shall see greater things than these." And to Nicodemus, "No man hath ascended up to heaven but the Son of man which is in heaven." What then, doth He add difficulties to difficulties? No, (that be far from Him,) but by the greatness of the doctrines, and the number of them, He desireth to bring them over. For if one had said simply, "I have come down from heaven," and added nothing more, he would have been the more likely to offend them; but He who said, "My body is the life of the world"; He who said, "As the living Father hath sent Me, so I live by the Father"; and who said, "I have come down from heaven," solves the difficulty. For the man who utters any one great thing concerning himself may perhaps be suspected of feigning, but he who connects together so many one after another removes all suspicion. All that He doth and saith is intended to lead them away from the thought, that Joseph was His father. And it was not with a wish to strengthen, but rather to do away that stumbling-block, that He said this. For whosoever deemed that He was Joseph's son could not receive His sayings, while one that was persuaded that He had come down from heaven, and would ascend thither, might more easily give heed to His words...

What then, if you see Me, in the appearance of the Son of Man, ascending into heaven, where I was before as God? For One and the Same ascends as Man to where He was before as God. He said this in order to draw …

"If then you shall see the Son of man ascending where he was before" — the construction is incomplete — then you will know that the flesh is not to be divided into pieces, because the whole Christ will be entire in heaven: Augustine: "He …