Hippocrates' greatest contribution to ancient neurosurgery is his book On Injuries of the Head, written around 400 BC. The book is a treatise on cranial anatomy and head trauma. Using the skills of observation, documentation, and examination, the author describes the anatomy of the skull, the different types of cranial trauma and fractures, the evaluation of the patient with head injury, and management, both operative and nonoperative. Hippocrates, like all ancient Greeks, was not a stranger to head trauma and its significance, given the numerous military conflicts that burdened ancient life. As reflected in the works of Homer, Herodotus, and Thucydides, it was recognized early that head wounds were especially dangerous and that when a head lesion was sufficiently significant, death was inevitable.