15 “And the day following He would go forth into Galilee, and finding Philip, He says unto him, Follow me. Now he was of the city of Andrew and Peter. And Philip finds Nathanael” (Philip who had been already called by the Lord); “and he said unto him, We have found Him, of whom Moses in the law, and the prophets, did write, Jesus, the son of Joseph.” He was called the son of that man to whom His mother had been espoused. For that He was conceived and born while she was still a virgin, all Christians know well from the Gospel.
This Philip said to Nathanael, and he added the place, “from Nazareth.” And Nathanael said unto him, “From Nazareth something good can come.” What is the meaning, brethren? Not as some read, for it is likewise wont to be read, “Can any good thing come out of Nazareth?” For the words of Philip follow, who says, “Come and see.” But the words of Philip can suitably follow both readings, whether you read it thus, as confirming, “From Nazareth something good can come,” to which Philip replies, “Come and see;” or whether as doubting, and making the whole a question, “Can any good thing come out of Nazareth? Come and see.” Since then, whether read in this manner or in that, the words following are not incompatible, it is for us to inquire which of the two interpretations we shall adopt.
Source: Tractates on the Gospel of John (New Advent)