The South Italian nature philosophers contributed much more to the science of medicine, and in certain of the colonial towns there were medical schools as early as the fifth century B.C.  The most famous of these physician philosophers was Pythagoras, whose life and work had an extraordinary influence upon medicine, particularly in connection with his theory of numbers, and the importance of critical days.  His discovery of the dependence of the pitch of sound on the length of the vibrating chord is one of the most fundamental in acoustics.  Among the members of the school which he founded at Crotona were many physicians. who carried his views far and wide throughout Magna Graecia.  Nothing in his teaching dominated medicine so much as the doctrine of numbers, the sacredness of which seems to have had an enduring fascination for the medical mind.  Many of the common diseases, such as malaria, or typhus, terminating abruptly on special days, favored this belief.  How dominant it became and how persistent you may judge from the literature upon critical days, which is rich to the middle of the eighteenth century.

One member of the Crotonian school, Alcmaeon, achieved great distinction in both anatomy and physiology.  He first recognized the brain as the organ of the mind, and made careful dissections of the nerves, which he traced to the brain.  He described the optic nerves and the Eustachian tubes, made correct observations upon vision, and refuted the common view that the sperma came from the spinal cord.  He suggested the definition of health as the maintenance of equilibrium, or an “isonomy” in the material qualities of the body.  Of all the South Italian physicians of this period, the personality of none stands out in stronger outlines than that of Empedocles of Agrigentum—­physician, physiologist, religious teacher, politician and poet.  A wonder-worker, also, and magician, he was acclaimed in the cities as an immortal god by countless thousands desiring oracles or begging the word of healing.  That he was a keen student of nature is witnessed by many recorded observations in anatomy and physiology; he reasoned that sensations travel by definite paths to the brain.  But our attention must be confined to his introduction of the theory of the four elements—­fire, air, earth and water—­of which, in varying quantities, all bodies were made up.  Health depended upon the due equilibrium of these primitive substances; disease was their disturbance.  Corresponding to those were the four essential qualities of heat and cold, moisture and dryness, and upon this four-fold division was engrafted by the later physicians the doctrine of the humors which, from the days of Hippocrates almost to our own, dominated medicine.  All sorts of magical powers were attributed to Empedocles.  The story of Pantheia whom he called back to life after a thirty days’ trance has long clung in the imagination.  You remember how Matthew Arnold describes him in the well-known poem, “Empedocles on Etna”—­