Orphism is the name given to a set of religious beliefs and practices originating in Thrace and later spreading to the ancient Greek and Hellenistic world, associated with literature ascribed to the mythical Thracian poet Orpheus, who descended into the Greek underworld and returned. This type of journey is called a katabasis and is the basis of several hero worships and journeys. Orphics revered Dionysus and Persephone. Orphism has been described as a reform of the earlier Dionysian religion, involving a re-interpretation or re-reading of the myth of Dionysus and a re-ordering of Hesiod's Theogony, based in part on pre-Socratic philosophy.