The Franciscan Roger Bacon (c.1214–92?) was one of the most significant intellectuals of the thirteenth century. His most important work was the Opus Majus of 1267 (also available in this series). The works included in this volume, edited by J. S. Brewer, had not previously been published, and only one volume of the unpublished works ever appeared, because of Brewer's other commitments. The Opus Minus was a précis of the larger work, written at the same time. The Opus Tertium, written the following year, was Bacon's attempt to cover topics which he felt had been omitted, or inadequately explained, in the previous versions; it also includes autobiographical information. Neither the Opus Minus or Opus Tertium survive in their entirety, but Brewer includes all the parts known in 1859. The Compendium Philosophiae deals with Bacon's wide-ranging intellectual interests in all aspects of medieval scholarship.