Jesus saw Nathanael coming toward him and said of him, "Here is a true Israelite. There is no duplicity in him." Nathanael said to him, "How do you know me?" Jesus answered and said to him, "Before Philip called you, I saw you under the fig tree." Nathanael answered him, "Rabbi, you are the Son of God; you are the King of Israel." Jesus answered and said to him, "Do you believe because I told you that I saw you under the fig tree? You will see greater things than this." And he said to him, "Amen, amen, I say to you, you will see the sky opened and the angels of God ascending and descending on the Son of Man." (Jn 1:47-51)
Nathanael believed in Jesus and exclaimed him to be the Son of God because Jesus recognized him even before he came to meet Jesus. That was, Jesus had played the role of a prophet (prophet in the sense of prediction). But the very same Nathanael did not believe when Philip told him about Jesus. In stead he questioned Philip saying ‘what good can come from Nazareth?’
Philip was assured that he would see greater things. He would see many miracles wrought by Jesus. The greater things that Jesus assured him would make him realize that Jesus was more than a prophet. Here Jesus bore witness to himself.
The greatest thing is that the sky would be opened. Heaven that was closed to man so far would now be opened in Jesus. The angels ascending and descending would mean that a link would be established between heaven and earth (The same idea is found in Gen 28:12, 17). Jesus would become the gateway to heaven, in a sense, Jesus would become the new Bethel (abode of God).
