John 16:4

"These things," therefore, He says, "have I told you, that, when their time shall come, ye may remember that I told you of them." These things, I say, I have told you, not merely because ye shall have to endure such things, but because, when the Comforter is come, He shall bear witness of me, that ye may not keep them back through fear, and by whom ye yourselves shall also be enabled to bear witness. "And these things I said not unto you at the beginning, because I was with you," and I myself was your comfort through my bodily presence exhibited to your human senses, and which, as infants, ye were able to comprehend.

"These things have I told you, that when the time shall come, ye may remember them." "So, judging from these words, deem the rest also trustworthy. For ye will not be able to say, that I flatteringly told you only those things which would please you, nor that the words were words of deceit; for one who intended to deceive, would not have told you beforehand of matters likely to turn you away. I have therefore told you before, that these things might not fall upon you unexpectedly, and trouble you; and for another reason besides, that ye might not say, that I did not foreknow that these things would be. Remember then that I have told you." And indeed the heathen always covered their persecutions of them by a pretense of their wickedness, driving them out as corrupters; but this did not trouble the disciples who had heard beforehand, and knew for what they suffered. The cause of what took place was sufficient to rouse their courage. Therefore He everywhere handleth this, saying, "they have not known Me"; and, "for My sake they shall do it"; and, "for My Name's sake, and for the Father's sake"; and, "I suffered first"; and, "from no just cause they dare these things."

(Tr. xciii) And He mentions these things beforehand, because trials, however soon to pass away, when they come upon men unprepared for them, are very overwhelming: But these things have I told you, that when the hour shall come, ye may remember that I told you of them: the hour, the hour of darkness, the hour of night. But the night of the Jews was not allowed to mix with or darken the day of the Christians. (Tr. xciv. 1) In the other three Evangelists these predictions occur before the supper; John gives them after. Still if they relate them as given very near His Passion, that is enough to explain His saying, These things I said not unto you at the beginning. Matthew however relates these prophecies as given long before His Passion, on the occasion of His choosing the twelve. How do we reconcile this with our Lord's words? By supposing them to apply to the promise of the Holy Spirit, and the testimony He would give amidst their suffering. This was what He had not told them at the beginning, and that because He was with them, and His presence was a sufficient consolation. But as He was about to depart, it was meet that He should tell them of His coming, by whom the love of God would be shed abroad in their hearts, to preach the word of God with boldness.