First published in 1941, this book contains the substance of the Linacre Lecture for that year, delivered by Sir Walter Langdon-Brown at St John's College, Cambridge. It presents a concise account regarding 'the origin of witchcraft from primitive religion and the part it played in the evolution of remedies through the magical phase to empirical success aided by laboratory investigation'. This book will be of value to anyone with an interest in the history of science and the development of medicine.