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)
In this passage Jesus presents himself as knowing the disciples even before meeting them. This knowledge makes the disciple to accept him as son of God. It is not the external knowledge alone that is spoken here (I saw you under the fig tree) but also the knowledge of the character of the person ("Here is a true Israelite. There is no duplicity in him.")
One disciple calls the other to Jesus (Philip calls Nathanael). In the Gospels of Matthew, Mark and Luke, Jesus goes around meeting the people and calling the disciples to follow him. In John’s gospel Andrew brought his brother Peter and now Philip brings Nathanael.
‘You will see the sky opened and the angels of God ascending and descending on the Son of Man’. Jews believed that there was place on earth which was the gate to heaven. And Bethel was considered to be that place because Jacob, in his dream, saw ladder touching the heavens and the angels descending. In this story Jesus says that he is the gate way to heaven.