This text consists of the earliest internal lectures by Steiner, transmitted through listener notes, within the framework of the Theosophical Society, where he connects to the Theosophy of that time while already preparing the fundamental elements of Anthroposophy. Content includes: I. About the astral world. The mystery of birth and death. The higher worlds and the human being's participation in them. The origin and nature of humanity. The beings of the astral world. The character of astral processes. Kamaloka II. The world of spirit or Devachan. The lower regions of Devachan. The Arupa realm. The activity of hierarchical beings. The passage of the human soul between death and new birth through the devachanic regions. Stages to attain knowledge of the spiritual world. The human aura. The post-mortem journey of the human soul. Seven regions of the spirit land. About initiation.