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.