Pneuma theory—Ancient Greece and Rome

Pneuma, according to ancient Greeks and Romans was a driving force in the body, necessary for maintaining bodily functions.

Pneuma was said by Aristotle and Plato to be a liquid-like substance forced through tubular nerves, causing the muscles to move. The reservoir of this pneuma was thought to be held in the cerebral ventricles, the rear one regulating the flow into the nervous system.

Subscribers to pneuma theory included

Alcmaeon (circa 500 bc) was the first to suggest that pneuma circulated within the arteries. Later, pneuma theory was elaborated upon by Plato (428-347 bc). Plato depicted life as involving multiple levels of pneuma by which he meant a person's soul or spirits. All levels arose from the vital organs. Inhaled air, emanating from God was transformed in the lungs into the first form of pneuma. Another form of pneuma or natural spirit was in the veins, which moved through the alimentary canal. When this venous fluid entered the heart it became transformed into a third, and higher form of pneuma, the vital spirit. This enriched pneuma past to the base of the brain where it was again transformed into the highest form of pneuma—animal spirit. Animal spirit, the essence of life, was, according to Plato, distributed through the body via the hollow nerves.

Erasistratus (260 BC) also believed in various types of interconnected pneuma, but they had a different course through the body. The first type, vital pneuma, came from air drawn through the trachea that was then changed into lung tissue. The vital pneuma, mixed with blood and then traveled in the arteries to the base of the brain where it was transformed into psychic pneuma. The psychic pneuma, sometimes referred to as animal spirit, aided the functioning of the brain and nerves. The third type of pneuma according to Erasistratus and then Galen was related to the humors in the brain.

Pneuma were at first considered to be inherent in the blood, not separate from it. Aristotle was the first to portray it as a fifth element, separate from air, water, fire and earth. For Aristotle, pneuma and humors worked together within the same channels. Praxagoras argued that vital pneuma traveled to the body from the left ventricle by way of the arteries. Erasistratus also thought the pneuma was breathed into the body via the nose as "vital heat" and traveled to the heart. Some of the vital heat passed through the brain. This vital heat provided the body with heat.

A Pneumatic School of physicians and scientists was founded in Rome by Athenaeus of Cilicia in the 1st century AD. Rufus of Ephesus was a member.

In Stoic philosophy, pneuma meant "breath of life." It was a mixture of the elements air (in motion) and fire (as warmth). It is the active element that organizes both the individual and the cosmos. In its highest form, the pneuma constitutes the human soul (psychê), which also contains the soul of the god Zeus. Pneuma, for the Stoics was also seen as a force that organizes matter, thereby existing in inanimate objects.

Writings about pneuma theory

Quin C. (1994). The soul and the pneuma in the function of the nervous system after Galen. Journal of the Royal Society of Medicine, 87, 393-395.