The Opus Majus of Roger Bacon (c.1214-92) is one of the most influential scientific and philosophical texts of its age and arguably the high point of medieval knowledge of the physical sciences. In the work Bacon makes a plea for the reform of education, emphasizing the rightful role of the sciences in the university curriculum and the interdependence of the various disciplines. Prepared in 1267 at the request of Pope Clement IV, the treatise is a collection of ideas, an encyclopedia of knowledge embracing all science, including language, logic, optics, mathematics, moral philosophy, and physics.

David Lindberg presents the first critical edition of the text of Roger Bacon's classic work Perspectiva, prepared from Latin manuscripts, accompanied by a facing-page English translation, critical notes, and a full study of the text. Also included is an analysis of Bacon's sources, influence, and role in the emergence of the discipline of perspectiva.

Investigating the impact of Arabic medieval astrological and magical theories on early modern occult philosophy, this book argues that they provided a naturalistic explanation of astral influences and magical efficacy based on Aristotelian notions of causality.

Back in thirteenth-century Europe, in the early years of the great universities, learning was spiced with the danger of mob violence and a terrifyingly repressive religious censorship. Roger Bacon, a humble and devout English friar, seems an unlikely figure to challenge the orthodoxy of his day - yet he risked his life to establish the basis for true knowledge. Born c.1220, Bacon was passionately interested in the natural world and how things worked. Such dangerous topics were vetoed by his Order, and it was only when a new Pope proved sympathetic that he began compiling his encyclopaedia on everything from optics to alchemy - the synopsis took a year and ran to 800,000 words and he was never to complete the work itself. Sadly, the enlightened Pope died, and Bacon was tried as a magician and incarcerated for ten years. Legend transformed Bacon into a sorcerer, 'Doctor Mirabilis', yet he taught that all magic was based on fraud, and his books were the first flowering of the scientific thinking that would transform our world. He advanced the understanding of optics, made geographical breakthroughs later used by Columbus, predicted everything from horseless carriages to the telescope, and stressed the importance of mathematics to science, a significance ignored for 400 years. His biggest contribution was to insist that a study of the natural world by observation and exact measurement was the surest foundation for truth. Clegg uncovers the realities of life in a medieval university and friary, setting out the shadowy facts of Bacon's life alongside his writings. The result is both a fascinating biography and a picture of the age.