QUADRIV'IUM (Lat., four branches of mathematics, place where four roads meet). The name given, in the language of the schools of the West, to the higher course of the mediæval studies, from its consisting of four branches, as the lower course, for an analogous reason, was called trivium (q.v.), or ‘three roads.’ The quadrivium consisted of arithmetic, music, geometry, and astronomy. These four studies compose the secondary part of the curriculum outlined by Plato in The Republic, and are described in the seventh book of that work. The history of this organization of human learning is briefly sketched in the article on Arts, Seven Liberal, where references to the literature of the subject will be found.