4 How much soever then we may understand, and how much soever we may see, we shall not see as the Son sees, even when we shall be made equal with the angels. For we are something even when we do not see; but what are we when we do not see, other than persons not seeing? And that we may see, we turn to Him whom we may see, and there is formed in us a seeing which was not before, although we were in being. For a man is when not seeing; and the same, when he does see, is called a man seeing. For him, then, to see is not the same thing as to be a man; for if it were, he would not be man when not seeing. But since he is man when not seeing, and seeks to see what he sees not, he is one who seeks, and who turns to see; and when he has well turned and has seen, he becomes a man seeing, who was before a man not seeing. Consequently, to see is to him a thing that comes and goes; it comes to him when he turns to, and leaves him when he turns away. Is it thus with the Son? Far be it from us to think so. It was never so that He was Son, not seeing, and afterwards was made to see; but to see the Father is to Him the same thing as to be Son. For we, by turning away to sin, lose enlightenment; and by turning to God we receive enlightenment. For the light by which we are enlightened is one thing; we who are enlightened, another thing. But the light itself, by which we are enlightened, neither turns away from itself, nor loses its lucidity, because as light it exists. The Father, then, shows a thing which He does to the Son, in such wise that the Son sees all things in the Father, and is all things in the Father. For by seeing He was begotten; and by being begotten He sees. Not, however, that at any time He was not begotten, and afterwards was begotten; nor that at any time He saw not, and afterwards saw. But in what consists His seeing, in the same consists His being, in the same His being begotten, in the same His continuing, in the same His unchanging, in the same His abiding without beginning and without end. Let us not therefore take it in a carnal sense that the Father sits and does a work, and shows it to the Son; and the Son sees the work that the Father does, and does another work in another place, or out of other materials. For “all things were made by Him, and without Him was nothing made.” The Son is the Word of the Father. The Father said nothing which He did not say in the Son. For by speaking in the Son what He was about to do through the Son, He begot the Son through whom He made all things.
5. “And greater works than these will He show Him, that you may marvel.” Here again we are embarrassed. And who is there that may worthily investigate this so great a secret? But now, in that He has deigned to speak to us, Himself opens it. For He would not speak what He would not have us understand; and as He has deigned to speak, without doubt He has excited attention: for does He forsake any whom He has roused to give attentive hearing? We have said that it is not in a temporal sense that the Son knows—that the knowledge of the Son is not one thing, and the Son Himself another; nor one thing His seeing, Himself another; but that the seeing itself is the Son, and the knowledge as well as the wisdom of the Father is the Son; and that that wisdom and seeing is eternal and co-eternal with Him from whom it is; that it is not something that varies by time, nor something produced that was not in being, nor something that vanishes away which did exist. What is it, then, that time does in this case, that He should say, “Greater works than these He will show Him”? “He will show,” that is, “He is about to show.” Hath shown is a different thing from will show: has shown, we say of an act past; will show, of an act future. What shall we do here, then, brethren? Behold, He whom we had declared to be co-eternal with the Father, in whom nothing is varied by time, in whom is no moving through spaces either of moments or of places, of whom we had declared that He abides ever with the Father seeing, seeing the Father, and by seeing existing; He, I say, here again mentioning times to us, says, “He will show Him greater works than these.” Is He then about to show something to the Son, which the Son does not as yet know? What, then, do we make of it? How do we understand this? Behold, our Lord Jesus Christ was above, is beneath. When was He above? When He said, “What things soever the Father does, these same also the Son does in like manner.” Whence know we that He is now beneath? Hence: “Greater works than these He will show Him.” O Lord Jesus Christ, our Saviour, Word of God, by which all things were made, what is the Father about to show You, that as yet You know not? What of the Father is hid from You? What in the Father is hid from You, from whom the Father is not hid? What greater works is He about to show You? Or greater than what works are they which He is to show You? For when He said, “Greater than these,” we ought first to understand the works than which are they greater.
Source: Tractates on the Gospel of John (New Advent)