This article on the essential teaching of great German mystic Meister Eckhart (c.1260−1328) is the result of many years of personal study. The article introduces to his anthropology and his scholastic theory of ecstasy and is divided into three chapters. The first chapter is an overview of heretical studies of man («Le Mirouer des simples ames» of M. Porete, anonymous «Schwester Katrei» etc.) from the 13−14 centuries which had an influence on Eckhart’s theology. The second and third chapters are a description of Eckhart’s study of ecstasy, that have in the author’s view a lot of common traits with the theological teaching of Byzantine theologian Gr.Palamas. The reseach is aimed to find a common approach to the comparison between German and Byzantine theology and mysticism of the late Middle Age.