 He saith unto him, Verily, verily, I say unto you, Hereafter ye shall see heaven opened, and the angels of God ascending and descending upon the Son of Man. The Jews understood the term Son of Man was referring to the Messiah. They had heard the Messiah would live forever. He was the Son of Man. But Jesus, who referred to himself as the Son of Man, was speaking of having to die. Turn with me to John chapter 12. The Jews didn't understand this.