St Gregory Palamas (d. 1359AD) commenting on the Gospel of the Transfiguration of Christ (Matthew 17:1-9) shows how the importance of the Gospel lesson is not in its historicity, but rather in what it reveals about humanity. Christ is revealing what it is to be human. Salvation consists in God restoring our full humanity to us. Christ in the Transfiguration is not simply revealing His divine glory – even more He is revealing the nature of humanity to bear divinity, to be united with God, to be deified.
“Before the transgression, Adam shared in this divine illumination and brilliance. He was clothed in the true robe of glory and was not naked, nor was he ugly in his nakedness, but was truly unspeakably better adorned than those who wear diadems embellished with much gold and precious stones. When our human nature was stripped of this divine illumination and radiance as a result of the ugly transgression, the Word of God had mercy on this nature and in His compassion took it upon Himself. On Mount Tabor he showed it clothed once more to His chosen disciples (Matthew 17:1-9, Mark 9:2-9, Luke 9:28-38, cf. 2 Pet. 1:16-18), proving to all what we had once been, and what those of us who believed in Him and attained to perfection in Him would be through Him in the age to come. You will find that the earnest of this perfection of those who live according to Christ is openly given here and now to God’s saints. They reap already, so to speak, the good of the age to come. Moses foreshadowed this, because the children of Israel could not gaze upon the glory of his face (Exod. 34:30-35).
Later, and more clearly, the Lord Himself shone so brightly on the mountain in the divine light that even the chosen disciples, who had received spiritual power from Him, could not stand and look at that radiance (Matt. 17:6), cf. Luke 9:34). Stephen’s face was like the face of an angel, according to the Scripture (Acts 6:15), and he looked up from the earth into the heights of heaven, where Christ sat on the right hand of the majesty, and he saw the heavenly glory of God (Acts 7:55-56). It would take too long to recount and tell at length of the others who received here the earnest of the good things to come and were blessed to obtain this divine illumination and radiance.” (The Homilies, pp 132-133)
We can see already in the lives of some of the saints the divine light shining through their humanity.