John 1: 50-51

Jesus said, “You believe because I told you I saw you under the fig tree. You shall see greater things than that.” He then added, “I tell you the truth, you shall see heaven open, and the angels of God ascending and descending on the Son of Man.”

Nathanael must have been amazed by the words of the Messiah.  For a mortal man to see Heaven opens, and angels ascending and descending on Jesus, must have sounded like science fiction of this time.  But Jesus was prophesying. Nathanael was most likely present at the River Jordan to repent, and be baptized. There people saw Heaven open, and Father God spoke to them about His anointed Son.