The condemnation of Roger Bacon

The condemnation of the English Franciscan Roger Bacon in 1277 has been the subject of a great deal of discussion, most of it inconclusive or misleading. There is ample evidence to suggest, however, that Bacon's condemnation and imprisonment resulted from his adherence to an astrological tradition, transmitted to Europe through the writings of Albumasar, which placed the birth of Christ and the advent of Christianity under the influence of a planetary conjunction of Jupiter and Saturn. In his works written for Pope Clement IV in the 1260s, Bacon treats this celestial phenomenon as an integral part of his astrological doctrine. Most of his contemporaries, including Thomas Aquinas and Albertus Magnus, reject the idea that the stars exerted an influence on the human nature of Christ at his birth. In contrast to the opinion of the noted historian of science, Lynn Thorndike, this article shows that Roger Bacon's views on this subject were indeed unique, and sufficiently heretical to warrant his condemnation and imprisonment by the Franciscan Order.