3 “And the servants and officers stood beside the fire of burning coals, for it was cold, and warmed themselves.” Though it was not winter, it was cold: which is sometimes wont to be the case even at the vernal equinox. “And Peter was standing with them, and warming himself. The high priest then asked Jesus of His disciples, and of His doctrine. Jesus answered him, I spoke openly to the world; I always taught in the synagogue, and in the temple, whither all the Jews resort, and in secret have I said nothing.
Why do you ask me? Ask those who heard me, what I have said unto them: behold, they know what I said.” A question occurs that ought not to be passed over, how it is that the Lord Jesus said, “I spoke openly to the world;” and in particular that which He afterwards added, “In secret have I said nothing.” Did He not, even in that latest discourse which He delivered to the disciples after supper, say to them, “These things have I spoken unto you in proverbs; but the hour comes, when I shall no more speak unto you in proverbs, but I shall show you plainly of my Father?” If, then, He spoke not openly even to the more intimate company of His disciples, but gave the promise of a time when He would speak openly, how was it that He spoke openly to the world?
And still further, as is also testified on the authority of the other evangelists, to those who were truly His own, in comparison with others who were not His disciples, He certainly spoke with much greater plainness when He was alone with them at a distance from the multitudes; for then He unfolded to them the parables, which He had uttered in obscure terms to others. What then is the meaning of the words, “In secret have I said nothing”? It is in this way we are to understand His saying, “I spoke openly to the world;” as if He had said, There were many that heard me.
And that word “openly” was in a certain sense openly and in another sense not openly. It was openly, because many heard Him; and again it was not openly, because they did not understand Him. And even what He spoke to His disciples apart, He certainly spoke not in secret. For who speaks in secret, that speaks before so many persons; as it is written, “At the mouth of two or three witnesses shall every word be established:” especially if that be spoken to a few which he wishes to become known to many through them; as the Lord Himself said to the few whom He had as yet, “What I tell you in darkness, that speak ye in light; and what ye hear in the ear, that preach ye upon the house-tops”? And accordingly the very thing that seemed to be spoken by Himself in secret, was in a certain sense not spoken in secret; for it was not so spoken to remain unuttered by those to whom it was spoken; but rather so in order to be preached in every possible direction.
A thing therefore may be uttered at once openly, and not openly; or at the same time in secret, and yet not in secret, as it is said, “That seeing, they may see, and not see.” For how “may they see,” save only because it is openly, and not in secret; and again, how is it that the same parties “may not see,” save that it is not openly, but in secret? Howbeit the very things which they had heard without understanding, were such as could not with justice or truth be turned into a criminal charge against Him: and as often as they tried by their questions to find something whereof to accuse Him, He gave them such replies as utterly discomfited all their plots, and left no ground for the calumnies they devised.
Therefore He said, “Why do you ask me? Ask those who heard me, what I have said unto them: behold, they know what I said.”
Source: Tractates on the Gospel of John (New Advent)