Origen
Catena Aurea · Matthäusevangelium 17
And his disciples asked him, saying, Why then say the Scribes that Elias must first come? And Jesus answered and said unto them, Elias truly shall first come, and restore all things. But I say unto you, That Elias is come already, and they knew him not, but have done unto him whatsoever they listed. Likewise shall also the Son of man suffer of them. Then the disciples understood that he spake unto them of John the Baptist.
That He says of John, Elias is already come, is not to be understood of the soul of Elias, that we fall not into the doctrine of metempsychosis, which is foreign to the truth of Church doctrine, but, as the Angel had foretold, he came in the spirit and power of Elias.