In this series of lectures, Rudolf Steiner illuminates from an unusual side the connection of man as a being with spirit, soul and body, with the surrounding worlds. Considering the formation of the human body during evolution, Author shows how a person, from incarnation to incarnation, acquires self-awareness and free thinking, and indicates which deviations from the norm in the internal organs lead to changes and deformation of the psyche. The Author considers the issues of dualism of thinking and will, peculiarities of memory, as well as the ability to love in connection with the influence of spiritual and cosmic forces. The book will be of interest not only to those interested in the work of R. Steiner, but also to teachers and medical workers.