(quatuor, four, and via, a road), the name given, in the language of the schools of the West, to the higher course of the medieval studies. From its consisting of four branches, as the lower course, for an analogous reason, was called Trivium, or "Three Roads." The quadrivium consisted of arithmetic, music, geometry, and astronomy. It would carry us beyond our limits to detail the nature and extent of each of these branches as pursued in the medieval schools. The reader will find much curious and new matter on all questions cf this nature in the volumes of the works of Roger Bacon, lately edited in the series issued under authority of the Master of the Rolls, as also in the Introduction prefixed to the volumes.