Why did Jesus call himself the Son of Man?
In the life of our Lord, meekness was as conspicuous as might. He declared his Sonship with God in John xvii: "These words spake Jesus, as he lifted up his eyes to Heaven and said, Father, the hour is come! Glorify Thy Son, that Thy Son also may glorify Thee." The hour had come for the avowal of this great truth, and for the proof of his eternal Life and sonship. Jesus' wisdom was known ofttimes by forbearing to speak, as well as by speaking, the whole truth. Haply he waited for a preparation of the human mind to receive startling announcements.
The disciples and prophets thrust disputed points on minds unprepared for them. This cost them their lives, and the world's temporary esteem. The prophecies were fulfilled, and their fidelity was rewarded by growth and spiritual understanding. Thus the immaculate conception and dual nature of Christ Jesus dawned by degrees on mortals. The Man of Sorrows knew, better than the Man of Joys, that his invisible self was the Son of God, and that mortal mind suffered, but not immortal Mind. He also recognized the human concept of this Son of God to be the Son of Man, as he sometimes called himself.