St. Gregory Palamas ca. 1296-1359
So, when the saints contemplate this divine light within themselves, seeing it by the divinising communion of the Holy Spirit, through the mysterious visitation of perfecting illuminations – then they behold the garment of their deification, their mind being glorified and filled by the grace of the Word, beautiful beyond measure in His splendour; just a the divinity of the Word on the mountain glorified with divine light the body conjoined to it. For “the glory which the Father gave Him”, He Himself has given to those obedient to Him, a the Gospel says, and “He willed that they should be with Him and contemplate His glory”. (Jn. 17:22,24)
How can this be accomplished corporeally, now that He Himself is no longer corporeally present after His ascension to the heavens? It is necessarily carried out in a spiritual fashion, for the mind becomes supercelestial, and as it were the companion of Him who passed beyond the heavens for our sake, since it is manifestly yet mysteriously united to God, and contemplates supernatural and ineffable visions, being filled with all the immaterial knowledge of a higher light. Then it is no longer the sacred symbols accessible to the senses that it contemplates, nor yet the variety of Sacred Scripture that it knows; it is made beautiful by the creative and primordial Beauty, and illumined by the radiance of God. (The Triads, B.5)