John 1:51 – “I tell all of you the solemn truth—you will see heaven opened and the angels of God ascending and descending on the Son of Man.”

The allusion is to the experience of Jacob (later re-named Israel), Gen 28:17.  While on his way to see Laban, he had a dream in which he say angels ascending and descending between heaven and earth.  He concluded that ‘the Lord is in this place’, and named it ‘Bethel’, meaning ‘the house of God’.

In comparing himself to Jacob, Jesus alludes to Gen 28:12.  In the midrashic traditions, the angels came to gaze upon Jacob, and even ascended and descended on him.  John’s readers were probably intended to understand Jesus as superior to Jacob.

According to DJG:

‘The allusion is to the patriarch Jacob’s vision of a ladder on which angels ascended and descended, linking heaven and earth. (Gen 28:10-17) Jesus appears to be telling Nathanael in a figurative way that once again God would reveal himself from heaven to the pious on earth, and that this revelation would directly involve Jesus as the Son of man.’ (cf. Jn 1:14,18 3:13)

‘Heaven opened’ possibly anticipates the descent of the Spirit at Jesus’ baptism (Mk 1:10).

There is no description elsewhere in John’s Gospel of angels moving between heaven and earth.  But, since angels are intermediaries of God’s presence and executors of his will, we may find a fulfilment of Jesus’ words in the very next chapter, when he ‘did this [miracle] as the first of his miraculous signs, in Cana of Galilee. In this way he revealed his glory.’  That glory is, of course, the incarnation of God and revelation of his character to human beings (Jn 1:14-18).

Jesus’ meaning seems to be, that his disciples will discern in his own life and ministry an unbroken communion with the Father, and an unrestricted commerce between heaven and earth.

Hard Sayings of the Bible concludes:

‘Jesus is the point of contact between God and the world. In him there is traffic between heaven and earth. That traffic is seen in his signs in which the presence of the glory of the Father in him shines through. This, John is saying, calls for belief. Nathanael committed himself to Jesus on the basis of what he had; we have far more basis for committing ourselves than he did.’

Nick Cady makes a number of points:

• There is no obvious record of this saying in the Gospels.  The nearest are Jesus’ baptism, transfiguration, and ascension; but none of these accounts mentions angels ascending and descending on Jesus.
• In Gen 11, the people of Babel had tried to build a tower, whose top reached the heavens.  Jesus is clearly alluding to the story of Jacob in Gen 28, which shows that God alone can span the gap between heaven and earth.
• Many scholars think that it was traditional for Jewish people to read the Scriptures while sitting under a fig tree.  It is possible that Nathanael was reading Gen 28, and that Jesus was interpreting it for him.  He is Jacob’s ladder!  It is he who spans the gap between heaven and earth.
• The ladder is not for us to climb up, but for God to descend (cf. Rom 10:6-9).