Nervous reflex arc. Engraving of a man standing next to fire with half his nervous system visible. The fire triggers a nervous impulse which travels up to the brain, into another nerve fibre and back to the leg muscles. The leg jerks away from the pain without any conscious thought in a reflex arc. Descartes originally planned to publish De homine in 1633, but hearing of Galileo’s condemnation by the Church, he became concerned for his own safety and refused to have it printed.

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René Descartes, Reflex Arc, Responding to Pain, 1633

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Photo credit: © Science History Images / Alamy / Afripics
License: Licensed
Model Released: No

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