I. Life 619 II. Criticism of and Part in Medieval Learning 630 III. Experimental Science 649 IV. Attitude Toward Magic and Astrology 659 62. THE SPECULUM ASTRONOMIAE 692 63. THREE TREATISES ASCRIBED TO ALBERT 720 64. EXPERIMENTS AND SECRETS: MEDICAL AND BIOLOGICAL 751 65. EXPERIMENTS AND SECRETS: CHEMICAL AND MAGICAL 777 66. PICATRIX 813 67. GUIDO BONATTI AND BARTHOLOMEW OF PARMA 825 68. ARNALD OF VILLANOVA 841 69. RAYMOND LULL 862 70. PETER OF ABANO 874 71. CECCO D’ASCOLI 948 72. CONCLUSION 969 INDICES: General 985 Bibliographical 1007 Manuscripts 1027 PREFACE This work has been long in preparation—ever since in 1902-1903 Professor James Harvey Robinson, when my mind was still in the making, suggested the study of magic in medieval universities as the subject of my thesis for the master’s degree at Columbia University—and has been foreshadowed by other publications, some of which are listed under my name in the preliminary bibliography. Since this was set up in type there have also appeared: “Galen: the Man and His Times,” in _The Scientific Monthly_, January, 1922; “Early Christianity and Natural Science,” in _The Biblical Review_, July, 1922; “The Latin Pseudo-Aristotle and Medieval Occult Science,” in _The Journal of English and Germanic Philology_, April, 1922; and notes on Daniel of Morley and Gundissalinus in _The English Historical Review_. For permission to make use of these previous publications in the present work I am indebted to the editors of the periodicals just mentioned, and also to the editors of _The Columbia University Studies in History, Economics, and Public Law_, _The American Historical Review_, _Classical Philology_, _The Monist_, _Nature_, _The Philosophical Review_, and _Science_. The form, however, of these previous publications has often been altered in embodying them in this book, and, taken together, they constitute but a fraction of it. Book I greatly amplifies the account of magic in the Roman Empire contained in my doctoral dissertation. Over ten years ago I prepared an account of magic and science in the twelfth and thirteenth centuries based on