That there is in Christ but one Hypostasis (i.e., Personal self).
But perhaps you think it a trifle to make this clear: not because it fails in clearness, but because the obscurity of unbelief always causes obscurity even in what is clear. Hear then how the Apostle sums up in a few words this whole mystery of the Lords unity [of Person]. “Our one Lord Jesus Christ,” he says, “by whom are all things.” 2460 O good Jesus, what weight there is in Thy words! For Thine they are, when spoken of Thee by Thine own. See how much is embraced in the few words of this saying of the Apostles. “One Lord,” says he, “Jesus Christ, by whom are all things.” Did he make use of any circumlocution in order to proclaim the truth of this great mystery? 2461 or did he make a long story of that which he wanted us to grasp? “Our one Lord,” he says, “Jesus Christ, by whom are all things.” In a plain and short phrase he taught the secret of this great mystery, through this confidence by which he realized that in what refers to God his statements had no need of lengthened arguments, and that the Divinity added faith to his utterances. For the demonstration of facts is enough to confirm what is said, whenever the proof rests on the authority of the speaker. There is then, he says, “one Lord Jesus Christ, by whom are all things.” Notice how you read the same thing of the Word of the Father, which you read of Christ. For the gospel tells us that “All things were made by Him, and without Him was not anything made.” 2462 The Apostle says, “By Christ are all things:” the gospel says, “By the Word are all things.” Do these sacred utterances contradict each other? Most certainly not. But by Christ, by whom the Apostle said that all things were created, and by the Word, by whom the Evangelist relates that all things were made, we are meant to understand one and the same Person. Hear, I tell you, what the Word of God, Himself God, has said of Himself. “No man,” he saith, “hath ascended into heaven, save He who came down from heaven, even the Son of man, who is in heaven.” 2463 And again He says: “If ye shall see the Son of man ascending where He was before.” 2464 He said that the Son of man was in heaven: He asserted that the Son of man had come down from heaven. What does it mean? Why are you muttering? Deny it, if you can. But do you ask the reason of what is said? However I do not give it you. God has said this. God has spoken this to me: His Word is the best reason. I get rid of arguments and discussions. The Person of the Speaker alone is enough to make me believe. I may not debate about the trustworthiness of what is said, nor discuss it. Why should I question whether what God has said is true, since I ought not to doubt that what God says is true. “No man,” He says, “hath ascended into heaven, save He who came down from heaven, even the Son of man, who is in heaven.” Certainly the Word of the Father was ever in heaven: and how did He assert that the Son of man was ever in heaven? You are then to understand that He showed that He who was ever the Son of God was also the Son of man: when He asserted that He, who had but recently appeared as the Son of man, was ever in heaven. To this points still more that other passage in which He testifies that the same Son of man; viz., the Word of God who, as He said, came down from heaven, even at the time when He was speaking on earth, was in heaven. For “no man,” He said, “hath ascended into heaven, save He who came down from heaven, even the Son of man who is in heaven.” Who, I pray you, is this who is speaking? Assuredly it is Christ. But where was He at the moment when He spoke? Assuredly on earth. And how can He assert that He came down from heaven when He was born, and that He was in heaven when He was speaking, or say that He is the same Son of man, when certainly no one but God can come down from heaven, and when He speaks on earth, and certainly cannot be in heaven except through the Infinite nature of God? Consider then this at last, and note that the Son of man is the same Person as the Word of God: for He is the Son of man since He is truly born of man, and the Word of God, since He who speaks on earth abideth p. 577 ever in heaven. And so when He truly terms Himself the Son of man, it refers to His human birth, while the fact that He never departs from heaven, refers to the Infinite character of His Divine nature. And so the Apostles teaching is admirably in accordance with those sacred words: (“for He that descended,” says He, “is the same that ascended also above all heavens, that He might fill all things,” 2465 ) when He says that He that descended is the same that ascended. But none can descend from heaven except the Word of God: who certainly “being in the form of God, emptied Himself, taking the form of a servant, being made in the likeness of men, and being found in fashion as a man, He humbled Himself, and became obedient unto death, even the death of the Cross.” 2466 Thus the Word of God descended from heaven: but the Son of man ascended. But He says that the same Person ascended and descended. Thus you see that the Son of man is the same Person as the Word of God.
1 Cor. viii. 6.576:2461
Tanti mysterii sacramentum.576:2462
S. John i. 3.576:2463
S. John iii. 13.576:2464
S. John vi. 63.577:2465
Eph. iv. 10.577:2466
Phil. ii. 6-8.