1 In this discourse we purpose speaking, as He gives us grace, on these words of the Lord which run thus: “I have manifested Your name unto the men whom You gave me out of the world.” If He said this only of those disciples with whom He had supped, and to whom, before beginning His prayer, He had said so much, it can have nothing to do with that clarification, or, as others have translated it, glorification, whereof He was previously speaking, and whereby the Son clarifies or glorifies the Father.
For what great glory, or what like glory, was it to become known to twelve, or rather eleven mortal creatures? But if, in saying, “I have manifested Your name unto the men whom You gave me out of the world,” He wished all to be understood, even those who were still to believe in Him, as belonging to His great Church which was yet to be made up of all nations, and of which it is said in the psalm, “I will confess to You in the great Church [congregation];” it is plainly that glorification wherewith the Son glorifies the Father, when He makes His name known to all nations and to so many generations of men.
And what He says here, “I have manifested Your name unto the men whom You gave me out of the world,” is similar to what He had said a little before, “I have glorified You upon the earth”,; putting both here and there the past for the future, as One who knew that it was predestinated to be done, and therefore saying that He had done what He had still to do, though without any uncertainty, in the future.
Source: Tractates on the Gospel of John (New Advent)