Light and enlightenment: Cabanis, ideology, and the role of phosphorus in the brain.

When Georges Cabanis presented his views to the National Institute of France in 1797 on the physiological basis of human psychology, he introduced the concept that phosphorus was of special importance in the workings of the brain. The presence of phosphorus in that organ had only recently been described by A F Fourcroy, a finding that impressed Cabanis because of the association of light (phosphorescence) and heat (evolved during oxidation) with the element. Furthermore, he hypothesised that the electrical activity of the brain represented a parallel and interacting system with that of phosphorus. Cabanis was one of the leading exponents of "ideology", the principal school of philosophy at the time of the French Revolution. Ideology promoted the systematisation of knowledge in every sphere--social, scientific and medical, for example-- and Cabanis's views about cerebral phosphorus evolved from those teachings.