Hastings' Dictionary of the Bible (1898)
SON OF MAN. Matt 8:20. T. It is also applied to him by Daniel. Dan 7:13. The Jews perfectly understood it to denote the Messiah. It sets forth his peculiar and intimate relation to mankind in his incarnate state, as the phrase "Son of God" denotes his peculiar relation to the divine Being. The phrase "the Son of man," however, does not express simply the humiliation and condescension of Christ, who became bone of our bone and flesh of our flesh, but also his exaltation above the ordinary level of humanity.
He calls himself, not a son of man (among other children of men), but the Son of man (above all others) - the ideal, the universal, the perfect Man. So, on the other hand, he calls himself not a, but the, Son of God - the only-begotten and eternal Son of the Father. Compare such passages as John 1:51; Joel 3:13; John 6:53; Matt 9:6; Neh 12:8; Matt 18:11; Mark 2:10, Acts 20:28.