3 Let no one disturb the clearness of the meaning by any cloudy contradiction; but let what follows furnish its testimony to the words that precede. For after saying, “I will that they also be with me where I am,” He went on immediately to add, “That they may behold my glory, which You gave me: for You loved me before the foundation of the world.” “That they may behold,” He said; not, that they may believe. This is faith's wages, not faith itself. For if faith has been correctly defined in the Epistle to the Hebrews as “the assurance [conviction] of things that are not seen,” why may not the wages of faith be defined, the beholding of things which were hoped for in faith?
For when we shall see the glory which the Father has given the Son, even though we may understand what is spoken of in this passage, not as that [glory] which the Father gave His co-equal Son in begetting Him, but as that which He gave Him, when become the Son of man, after the death of the cross;— when, I say, we shall see that glory of the Son, then of a certainty shall take place the judgment of the quick and the dead, and then shall the wicked be taken away that he may not behold the glory of the Lord; and what [glory], save that of His Godhead?
For blessed are the pure in heart, for they shall see God: and because the wicked are not pure in heart, therefore they shall not see. Then shall they go away into everlasting punishment; for so shall the wicked be taken away, that he may not behold the glory of the Lord: but the righteous shall go into life eternal. And what is life eternal? “That they may know You, the only true God, and Jesus Christ, whom You have sent”: not, indeed, as those knew Him, who although impure in heart, yet were able to see Him as He sat in judgment in His glorified servant-form; but as He is yet to be known by the pure in heart, as the only true God, the Son along with the Father and Holy Spirit, because the Trinity itself is the only true God.
If, then, it is in reference to His Godhead as the Son of God, equal and co-eternal with the Father, that we take the words, “I will that they also be with me where I am,” we shall be with Christ in the Father; but He in His own way, we in ours, wherever we may be in body. For if localities are to be understood, and such as contain incorporeal beings, and everything has a place where it is, the eternal place of Christ where He always is, is the Father Himself, and the place of the Father is the Son; for “I,” He said, “am in the Father, and the Father in me;” and in this prayer, “As Thou, Father, art in me, and I in You:” and they are our place, because there follows, “That they also may be one in us:” and we are God's place, inasmuch as we are His temple; even as He, who died for us and lives for us, also prays for us, that we may be one in them; because “His [dwelling] place was made in peace, and His habitation in Zion,” which we are.
But who is qualified to think on such places or what is in them, apart from the idea of space-defined capacities and material masses? Yet no little progress is made, if at least, when any such idea presents itself to the eye of the mind, it is denied, rejected, and reprobated: and a certain kind of light is, as far as possible, thought of, in which such things are perceived as deserving only to be denied, rejected, and reprobated; and the certainty of that light is known and loved, so that from thence an upward movement is begun in us, and an effort made to reach into places farther within: and when the mind through its own infirmity and still inferior purity has failed to penetrate them it is driven back again, not without the sighings of love and the tears of ardent longing, and continues to bear in patience until it is purified by faith, and prepared by the holiness of the inward life to be able to take up its abode therein.
Source: Tractates on the Gospel of John (New Advent)