Even his contemporaries praised the Greek physician Hippocrates of Kos for his healing arts. His knowledge was so outstanding that his writings acted as a crystallization point for the medical texts of other doctors and formed a unity in the tradition known as the Corpus Hippocraticum. Of timeless significance is the most famous piece of this collection, which has entered history as the Hippocratic Oath; to this day, it serves as a benchmark for the ethical conduct of a physician. What did Hippocrates (circa 460 to circa 380 BC), the doctors of his time, and those of the following centuries really know about humans? What ideas did they have about the human body and the connections that are causative in the development of diseases? What triggers did they suspect, for example, behind epidemics, behind an epileptic seizure, or behind...