Origen
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.
(in Joan. tom. vi. c. 7) Some one will say that John was ignorant that he was Elias; as those say, who maintain, from this passage the doctrine of a second incorporation, as though the soul took up a new body, after leaving its old one. For the Jews, it is said, asking John by the Levites and priests, whether he is Elias, suppose the doctrine of a second body to be already certain; as though it rested upon tradition, and were part of their secret system. To which question, however, John replies, I am not Elias: not being acquainted with his own prior existence. But how is it reasonable to imagine, if John were a prophet enlightened by the Spirit, and had revealed so much concerning the Father, and the Only-Begotten, that he could be so in the dark as to himself, as not to know that his own soul had once belonged to Elias?