The trifunctional hypothesis of prehistoric Proto-Indo-European society postulates a tripartite ideology ("idéologie tripartite") reflected in the existence of three classes or castes—priests, warriors, and commoners (farmers or tradesmen)—corresponding to the three functions of the sacral, the martial and the economic, respectively. The trifunctional thesis is primarily associated with the French mythographer Georges Dumézil who proposed it in 1929 in the book Flamen-Brahman, and later in Mitra-Varuna.