"There is no beauty that we should desire him" (Isaiah 53:2)
Think about the glory of our Lord that we are told about when He was on earth: "There was no beauty that we should desire him ... a man of sorrows, and acquainted with grief" (Isaiah 53:2-3). People would look at Him and say, "Who is this fellow?" "Is not this the carpenter, the son of Mary?" (Mark 6:3). He had laid aside the glory; He had not laid aside anything of His essential being or person or His essential deity. But neither had He held on to it. He had not clutched at the manifestation of His glory. He had laid that aside as one would a cloak and had come in the likeness of man.
Indeed, I must go further than this, because this is the wonder of it all. He decided that His glory should be veiled by flesh. Think of it like this: The glory is there still shining in all its power, but a veil of flesh has come over it so that mankind cannot see it.
Take an Old Testament illustration. In the wilderness Moses went onto the Mount and spoke with God, and when he came down his face was shining. The people saw the glory, and it was so bright that he had to put a veil over his face; the glory was still there, but it was hidden from them. Something like that happened to our Lord.
Yes, but He not only came as man, nor is it only true to say that His glory was veiled by flesh. It is not true to say simply that the eternal Son of God was made flesh. We are told that he was made "in the likeness of sinful flesh" (Romans 8:3). Indeed, He not only came into this world as a man - He took on Him "the form of a servant" (Philippians 2:7). It would have been a wonderful and astounding thing if this eternal King and Prince of glory had come on earth and lived in a palace as a human king with all the pomp and glory of an earthly kingship. But that is not what He did at all! He was born as a babe in very poor circumstances.