St Gregory Palamas’s Homily on the Transfiguration
Thus, this Light is not a light of the senses, and those contemplating it do not simply see with sensual eyes, but rather they are changed by the power of the Divine Spirit. They were transformed, and only in this way did they see the transformation taking place amidst the very assumption of our perishability, with the deification through union with the Word of God in place of this.