The authors take into consideration the philosophical foundations of the Byzantine Hesychasm in the context of interrelationship between the human being and God in the uncreated Divine Light. Some doctrines that precede the late Hesychasm and Gregory Palama and Palamites’ teaching are analyzing in this sense. The forming of Hesychasm as a trend of the Byzantine thought is discussed in the article, starting from the early period of the history of the Eastern Christian Empire. The article gives a survey of conceptions by Hermit Fathers (Evagrius Ponticus, and Macarius of Egypt), John Climacus, Maximus the Confessor, Gregory of Sinai. The most important philosophical ideas of the Eastern Patristics are presented as a gradual emergence of the coherent mystical Christian doctrine of the Hesychasm. The authors pay a special attention to the reflection of the anthropological and epistemological provisions of the theology of Gregory Palama. The peculiarity of the Hesychast religious gnosis is considered. The essence of the God-knowing process is reflected by the Byzantine thinker’s teaching about the transfigured nature of the human being, that has become perfect and deified due to the deep perception of the Divine light. The Hesychast Tabor light is a mean of the human and God’ spiritual unity that converted a nature of an individual into luminous beginning. The movement to the luminous transfiguration of the human is demonstrated as a twofold process — from God to the human and, vice versa, from the human to God. © 2024 Saint Petersburg State University. All rights reserved.