Hermeticism, also called Hermetism, is a religious, philosophical, and esoteric tradition based primarily upon writings attributed to Hermes Trismegistus ("Thrice Great"). These writings have greatly influenced the Western esoteric tradition and were considered to be of great importance during both the Renaissance and the Reformation. The tradition claims descent from a prisca theologia, a doctrine that affirms the existence of a single, true theology that is present in all religions and that was given by God to man in antiquity.