Ancient Greek practices and philosophy stressing a movement in the world from cosmic order, represented mythologically by an original primordial egg, to a gradually developing disorder. Most scholars agree that by the 5th century BCE the Orphic movement existed, with travelling priests who offered teaching and initiation, based on a body of legend and doctrine said to have been founded by Orpheus.

Source: Art & Architecture Thesaurus

http://vocab.getty.edu/page/aat/300400850