John 3:12

The expression "earthly things," some say is here used of the wind; that is, "If I have given you an example from earthly things, and ye did not even so believe, how shall ye be able to learn sublimer things?" And wonder not if He here call Baptism an "earthly" thing, for He calls it so, either from its being performed on earth, or so naming it in comparison with that His own most awful Generation. For though this Generation of ours is heavenly, yet compared with that true Generation which is from the Substance of the Father, it is earthly. He does not say, "Ye have not understood," but, "Ye have not believed"; for when a man is ill disposed towards those things which it is possible to apprehend by the intellect, and will not readily receive them, he may justly be charged with want of understanding; but when he receives not things which cannot be apprehended by reasoning, but only by faith, the charge against him is no longer want of understanding, but unbelief. Leading him therefore away from enquiring by reasonings into what had been said, He touches him more severely by charging him with want of faith. If now we must receive our own Generation by faith, what do they deserve who are busy with their reasonings about that of the Only-Begotten?

"If I have told you earthly things, and ye believe not; how shall ye believe, if I tell you heavenly things?" What earthly things did He tell, brethren? "Except a man be born again;" is that an earthly thing? "The Spirit bloweth where it listeth, and thou hearest its voice, and knowest not whence it cometh, or whither it goeth;" is that earthly? For if He spoke it of the wind, as some have understood it, when they were asked what earthly thing the Lord meant, when He said, "If I told you earthly things, and ye believe not; how shall ye believe, if I tell you heavenly things?" Now what did He name earthly? He was speaking of the spiritual birth; and going on, saith, "So is every one that is born of the Spirit." Then, brethren, which of us does not see, for example, the south wind going from south to north, or another wind coming from east to west? How, then, know we not whence it cometh and whither it goeth? What earthly thing, then, did He tell, which men did not believe? Was it that which He had said about raising the temple again? Surely, for He had received His body of the earth, and that earth taken of the earthly body He was preparing to raise up. They did not believe Him as about to raise up earth. "If I told you earthly things," saith He, "and ye believe not; how shall ye believe if I tell you heavenly things?" That is, if ye believe not that I can raise up the temple cast down by you, how shall ye believe that men can be regenerated by the Spirit?

(Tr. xii. in Joan. c. 7) That is: If ye do not believe that I can raise up a temple, which you have thrown down, how can ye believe that men can be regenerated by the Holy Ghost?