To bestow a consonant measure of deification on created beings is within the power of divine grace alone. Grace irradiates nature with a supernatural light and by the transcendence of its glory raises nature above its natural limits.
Maximos the Confessor establishes divine grace as the sole ontological agent capable of deification, since created nature lacks the intrinsic capacity to grasp or communicate God.
, The Philokalia, Volume 1, 1979thesis