10 lectures, Helsinki, April. 3 14, 1912 (CW 136)In the architecture of Rudolf Steiner s great cosmological temple, this extraordinary course of lectures on spiritual beings forms the central pillar with other important texts such as the fourth chapter of "An Outline of Esoteric Science" (CW 13); "The Spiritual Hierarchies and the Physical World" (CW 136); and "Inner Experiences of Evolution" (CW 132). These works outlining a revolutionary angelological cosmology are at the heart of Steiner s mission to transform our understanding of the world by laying down a new, non-dual, phenomenological path to a contemporary divine-spiritual-physical cosmology that is angelological and theophanic. For Steiner, what constitutes the world are beings including the ground of the world itself, the Father being. Steiner s cosmology or angelology is personal, and it is known in relationship; therefore, he presents it in terms of states and deeds of conscious, and of the divine-spiritual beings whose states and deeds they are. The spiritual world is thus always a world of beings. The twin realizations "I am an I being" and "reality is constituted of other I beings" go together. Cosmology is angelology. Spiritual beings define experience of the nature of reality. In these lectures, the reader is led through a series of meditations to recognize these spiritual beings and come to know their deeds. Steiner s approach is contemporary in that, while continuous with the most ancient understanding of the cosmos, he discovers it for himself, out of his own experience and consciousness, and expresses it in his own words with a logic and language appropriate to our time. Thus he teaches us, his readers, to do the same. In these lectures, the reader is led through a series of meditations to recognize and come to know the activities and beings of the nine angelic hierarchies: seraphim (Spirits of Love) cherubim (Spirits of Harmony) thrones (Spirits of Will) dominions (Spirits of Wisdom) virtues (Spirits of Movement) powers (Spirits of Form) principalities (Spirits of Personality) archangels (Spirits of Fire) angels (Sons of Life) Steiner s achievement in these lectures, as Valentin Tomberg said, cannot be compared with the accomplishment of any contemporary seer or thinker, or with any of the Middle Ages or antiquity. It towers over them. This book is a translation from German of the book "Die geistigen Wesenheited in den Himmelskorpern und Naturreichen" (GA 136). Translator unknown; original translation revised by Marsha Post."