Fr. Roger Bacon: Opus Tertium, Opus Minus, Compendium Philosophiae (1859) is a book written by John Sherren Brewer. The book is a collection of three works by the medieval philosopher and theologian Roger Bacon. The first work, Opus Tertium, is an extensive treatise on natural philosophy, theology, and mathematics. The second work, Opus Minus, is a shorter version of Opus Tertium, which Bacon wrote at the request of Pope Clement IV. The third work, Compendium Philosophiae, is a summary of the principles of natural philosophy, ethics, and logic. The book provides a comprehensive overview of Bacon’s philosophical and theological ideas, which were highly influential in the medieval period. Bacon was one of the first scholars to advocate for the use of empirical observation and experimentation in natural philosophy, and his works were instrumental in the development of modern science. Brewer’s edition of Bacon’s works includes extensive notes and commentary, which help to contextualize Bacon’s ideas within the broader intellectual and historical context of the medieval period. The book is an important resource for scholars of medieval philosophy and theology, as well as for anyone interested in the history of science and the development of Western intellectual thought.This scarce antiquarian book is a facsimile reprint of the old original and may contain some imperfections such as library marks and notations. Because we believe this work is culturally important, we have made it available as part of our commitment for protecting, preserving, and promoting the world’s literature in affordable, high quality, modern editions, that are true to their original work.