The author proves that the cult of Osiris was the most popular and enduring in any ancient religion. She shows how it provided direct antecedents for many ideas, traits, and customs in Christianity, including the resurrection after three days, the concept of god as trinity, baptism in the sacred river, and the sacrament of the Eucharist. She also reveals the cult's influence on other Western mystical traditions and groups, such as the Alchemists, Rosicrucians, and Freemasons.