Alcmaeon of Croton

Early 5th C BC

Alcmaeon of Croton was an early Greek medical writer and philosopher-scientist. His book later called On Nature focused primarily on issues of psychology and epistemology. He was first to identify the brain as the seat of understanding and to distinguish understanding from perception. He was also the first to develop an argument for the immortality of the soul.

Alcmaeon thought that the sensory organs were connected to the brain by channels. He may have discovered the optic nerve by excising the eyeball of an animal.

Alcmaeon, like others of his times, used humor theory to depict health and disease. He depicted a healthy body as arising from a balance of the humors in the body. Domination of one humor over the others, he argued, results in disease. In humor theory, humor balance is affected by temperature, which in turn results from an excess or deficiency in nutrition. Fever, or excess heat, was treated by cooling the patient, and dryness in the body was treated by adding moisture. The goal of treatment was to restore equilibrium of the humors.

Alcmaeon discussed wide range of topics in his book On Nature, including physiology, sleep, death and the development of the embryo. His ideas had considerable impact on his successors in the Greek philosophical tradition.

Alcmaeon was highly influential. Aristotle wrote a treatise responding to Alcmaeon and Plato adopted Alcmaeon’s argument for the immortality of the soul. A number of physicians and philosophers accepted Alcmaeon’s view that the brain is the seat of intelligence, including Plato (d. 347 BC), some followers of Hippocrates (5th to 2nd C BC), and the Alexandrian physicians, Herophilus and Erasistratus (C. 300 BC).

Writings about Alcmaeon on the web

Alcmaeon retrieved from on January 10, 2010