Augustine of Hippo — as excerpted in the Catena Aurea on John 6:60-71

“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.”