This book is the self-described "spiritual autobiography" of Olivia Robertson. In it, Olivia describes her personal adventures in the occult and mystical fields. The Call of Isis was first published in 1975, one year before the Fellowship of Isis was founded. It is her original account of meditative journeys, as well as a variety of spiritual experiences, of friends and fellow seekers. Robertson outlines the threefold stage of initiation; that of the moon, the sun and stars. This new edition also contains material on the Fellowship of Isis which was not included in the original edition.