John Calvin Commentary John 1:51

"And he saith unto him, Verily, verily, I say unto you, Ye shall see the heaven opened, and the angels of God ascending and descending upon the Son of man." — John 1:51 (ASV)

You shall see heaven opened. In my opinion, those who anxiously inquire into the place where, and the time when, Nathanael and others saw heaven opened are greatly mistaken; for He rather points out something perpetual that was always to exist in His kingdom. Indeed, I acknowledge that the disciples sometimes saw angels, who are not seen today; and I also acknowledge that the manifestation of the heavenly glory, when Christ ascended to heaven, was different from what we now behold.

But if we properly consider what took place at that time, it is perpetual; for the kingdom of God, which was previously closed to us, is actually opened in Christ. A visible instance of this was shown to Stephen (Acts 7:55), to the three disciples on the mountain (Matthew 17:5), and to the other disciples at Christ’s ascension (Luke 24:51; Acts 1:9). But all the signs by which God shows Himself present with us depend on this opening of heaven, especially when God communicates Himself to us to be our life.

Ascending and descending on the Son of man. This second clause refers to angels. They are said to ascend and descend, so as to be ministers of God’s kindness toward us; and therefore, this way of speaking points out the mutual interaction that exists between God and men. We must acknowledge that this benefit was received through Christ, because without Him, the angels would rather have a deadly enmity against us than a friendly care to help us.

They are said to ascend and descend on the Son of Man, not because they minister to Him, but because—in reference to Him, and for His honor—they include the whole body of the Church in their kindly regard. Nor do I have any doubt that He alludes to the ladder that was shown to the patriarch Jacob in a dream (Genesis 28:12); for what was prefigured by that vision is actually fulfilled in Christ.

In short, this passage teaches us that, although the whole human race was banished from the kingdom of God, the gate of heaven is now opened to us, so that we are fellow-citizens of the saints and companions of the angels (Ephesians 2:19); and that they, having been appointed to be guardians of our salvation, descend from the blessed rest of the heavenly glory to relieve our distresses.