The flesh of Christ, it is said, is glorified at the moment of its assumption and the glory of the Godhead becomes the body’s glory. But this glory was invisible in His visible body to those unable to perceive that upon which even angels cannot gaze. Thus Christ was transfigured, not by the addition of something He was not, nor by a transformation into something He was not, but by the manifestation to His disciples of what He really was. He opened their eyes so that instead of being blind they could see. While He Himself remained the same, they could now see Him as other than He had appeared to them formerly. For He is ‘the true light’ (John 1:9), the beauty of divine glory, and He shone forth like the sun – though this image is imperfect, since what is uncreated cannot be imaged in creation without some diminution.
~ St. Gregory Palamas (+1359)