John Calvin on John 16:7

7. Yet I tell you the truth. That they may no longer wish to have him present before their eyes, he testifies that his absence will be advantageous, and makes use of a sort of oath; for we are carnal, and consequently nothing is more difficult than to tear from our minds this foolish inclination, by which we attempt to draw down Christ from heaven to us. He explains where the advantage lies, by saying that the Holy Spirit could not be given to them, if he did not leave the world. But far more advantageous and far more desirable is that presence of Christ, by which he communicates himself to us through the grace and power of his Spirit, than if he were present before our eyes. And here we must not put the question, “Could not Christ have drawn down the Holy Spirit while he dwelt on earth?” For Christ takes for granted all that had been decreed by the Father and, indeed, when the Lord has once pointed out what he wishes to be done, to dispute about what is possible would be foolish and pernicious.

John 16:8-15

8. And when he is come, he will convince the world of sin, and of righteousness, and of judgment 9. Of sin, because they believe not in me 10. Of righteousness, because I go to my Father, and you see me no more. 11. Of judgment, because the prince of this world hath been judged. 12. I have yet many things to say to you, but you cannot bear them now. 13. But when he, the Spirit of truth, is come, he will lead you into all truth; for he will not speak from himself, but will speak all that he has heard, and will declare to you the things that are to come. 14. He will glorify me, for he will take of what is mine, and will declare it to you. 15. All things that the Father hath are mine; therefore I said to you, He will take of what is mine, and will declare it to you.