The book investigates the structure and nature of spiritual hierarchies as understood within esoteric traditions. Arthur Edward Waite, a prominent scholar of the occult and mystical traditions, draws upon a wide range of historical and philosophical sources to delineate the various orders and ranks of spiritual beings. The work aims to provide a systematic framework for understanding the divine and angelic realms, exploring their influence on the material world and human consciousness. It presents a complex cosmology intended for serious students of mysticism.

This work is regarded as a significant contribution to the study of Western esotericism, offering a scholarly yet accessible overview of complex spiritual structures. Waite's meticulous research and clear exposition make it a valuable resource for those interested in the history of occult thought and mystical philosophy. The book is often cited for its comprehensive approach to understanding the organization of the spiritual cosmos. Its enduring relevance lies in its detailed exploration of concepts that continue to fascinate scholars and practitioners alike.