Gregory the Great
Catena Aurea · Johannesevangelium 1
And this is the record of John, when the Jews sent priests and Levites from Jerusalem to ask him, Who art thou? And he confessed, and denied not; but confessed, I am not the Christ. And they asked him, What then? Art thou Elias? And he saith, I am not. Art thou that prophet? And he answered, No. Then said they unto him, Who art thou? that we may give an answer to them that sent us. What sayest thou of thyself? He said, I am the voice of one crying in the wilderness, Make straight the way of the Lord, as said the prophet Esaias. And he said, I am not.
(Hom. vii. in Evang. c. 1) But if we examine the truth accurately, that which sounds inconsistent, will be found not really so. The Angel told Zacharias concerning John, He shall go before Him in the spirit and power of Elias. (Luke 1:17) As Elias then will preach the second advent of our Lord, so John preached His first; as the former will come as the precursor of the Judge, so the latter was made the precursor of the Redeemer. John was Elias in spirit, not in person: and what our Lord affirms of the spirit, John denies of the Person: there being a kind of propriety in this; viz. that our Lord to His disciples should speak spiritually of John, and that John, in answering the carnal multitude, should speak of his body, not of his spirit.