An Outline of Esoteric Science is Rudolf Steiner's most complete and methodical presentation of the results of his own spiritual research. Written in 1909, when he was forty-eight years old, it represents his mature thinking, yet also has the careful structure and development characteristic of the work of young authors. The title points out that the subject of the book is just those realities and beings which are, at least initially, hidden from most of us. But at the same time, it makes explicit that this is not collection of "tales of the supernatural," but a clear, conceptual, thoroughly scientific account of these matters. The book is terse, concise, and demands the reader's utmost attention, as well as the energy to visualize inwardly the pictures presented. It is not a book to be skimmed. Nor is it to be sampled here and there-though one man who tried to do so hit a passage that changed his life. - Clopper Almon, from the introduction With the commentary in the Study Companion keyed by paragraph number to the text of An Outline of Esoteric Science, Clopper Almon takes the reader step-by-step through one of Rudolf Steiner's most difficult texts. Each chapter is considered for themes, or brief summaries of the main points, review questions, discussion questions, and Almon's own observations of the text. This study companion will be a great help to readers of every level, vastly enriching their reading of one of Steiner's most important written works.