Thomas Heyne, M.D., M.St. Oxon.: Nemesius the Neurologist: Dissecting the Brain in De Natura Hominis

Although Nemesius of Emesa (c.390) was a bishop rather than a physician, he demonstrates a deeper knowledge of anatomy and physiology than arguably any prior Christian author. Nemesius’ De Natura Hominis adapts Plato, Aristotle, Hippocrates, and particularly Galen to discuss the various parts of the body as evidence of God’s creative skill. Most impressive is Nemesius’ discussion of the central nervous system: the brain and connected nerves. Using Galen and surpassing any prior Christian author, Nemesius describes the spinal cord and its connection to movement, as well as the five senses and their nervous connections to the brain. Going beyond even Galen, Nemesius is the first author to lay out a cohesive, evidence-based attempt at “brain mapping,” localizing the different activities of the mind/soul to specific areas of the brain. Specifically, Nemesius localizes sensation, thought, and memory to the anterior, middle, and posterior brain ventricles, respectively; he then discusses “patient cases” to defend his view. He also localizes movement to the spinal cord and posterior ventricle. Such neurology supported his anthropology, viz., man as an intimate unity of soul and body. Although some have argued that Nemesius relied on Posidonius of Byzantium, there is limited evidence for this hypothesis. Instead, Nemesius is the first-known author to exposit clearly the “ventricular theory”, which dominated medieval thought for centuries. Furthermore, his attempt at “brain mapping” is continued by neuropsychologists to this day. Thus, Nemesius is an example of the positive, thoughtful approach that many early Christian writers took to medicine.