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.