The kingdom of heaven consists in possessing an inviolate and pre-eternal knowledge of created things through perceiving their inner essences as they exist in God.
This passage provides the most technically precise definition in the corpus, distinguishing the Kingdom of Heaven (gnostic apprehension of essences) from the Kingdom of God (gracious participation in divine attributes), both anchored in the Lucan dictum that the Kingdom is within.
, The Philokalia, Volume 4, 1995thesis