Hippocrates, who came from the Aegean island of Cos, is said to have been born in 460 BCE. His legendary status as the father of medicine is secure—unfortunately, just about everything else about him is legendary too. Tradition records a number of entertaining stories, but it is plain that later writers in the notoriously unreliable Greek biographical tradition knew very little about him. Plato mentions him a couple of times, respectfully, and in Phaedrus (270b–d) ascribes approvingly to him the view that in order to know the parts of something one must know the whole. But there is no consensus even as to what the whole here refers to: The whole of the universe? Or simply the complete structure of the body? Different scholars, taking different lines, have consequently seen this remark as alluding to...