This book examines the Franciscan alchemist Roger Bacon’s (1220-1292) interest in the role of alchemy in medicine, and how this interest connected with the thirteenth-century milieu in which he was writing. Though twelfth-century Latin alchemy had largely been concerned with transmuting base metals into noble ones, Bacon believed that the natural principles taught in alchemy would be better used in medicine. In an age where many physicians were theorizing about ways to prevent the effects of aging, Bacon held that combining alchemy and humoral medicine would allow one to extend their life...