This book examines the history of magic and experimental science and their relation to Christian thought during the first 13 centuries AD, with particular attention to the 12th and 13th centuries. No one has yet made a complete survey of the history of magic and experimental science during this period, so I had to process a large number of manuscripts. Magic in this book is understood in the broadest sense of the word and includes all the occult arts and sciences, superstition and folklore. I will try to justify the use of this term with the help of all the sources that I have studied. My idea is that the development of magic and experimental science was closely intertwined, that sorcerers and magicians were probably the first to turn to experiment, so the history of magic and experimental science will become clearer if they are studied together. I also want to make the Latin science of the medieval period clearer than it was for most scholars (we generally know very little about the leading scientists of this period) and probably no issue needs to be covered more than the one we have touched on in this book. Laws against magic, folk signs of magic, persecution and execution of witches remained beyond the scope of my research.