Philosophumena; or, The refutation of all heresies, Volume I

The work surveys and critiques a wide range of ancient religious and philosophical systems, opening with summaries of Greek philosophers and later treating diviners, astrologers, mathematical seers, and magic, then examining various Gnostic and heretical sects through quotations from now-lost texts. The author argues that heterodox doctrines arise from syncretism with pagan philosophy and occult practices rather than scriptural error, catalogues sectarian teachings (including Ophite, Sethian, Naassene, Basilidian, and Valentinian strands), and records practices, rituals, and doctrinal formulations while interweaving polemical rebuttal and moral censure.