GEORGE BERNARD / SCIENCE PHOTO LIBRARY GEORGE BERNARD / SCIENCE PHOTO LIBRARY
Nervous coordination. Engraving showing nervous coordination of arm movement from the first European textbook of physiology, Rene Descartes' De Homine (1662). Nervous impulses from the brain travel down into the arm triggering muscle contractions which bend the arm into position B. Muscles (at lower and far left) are shown on the outline of the arm's former position at C. Descartes (1596-1650) was a French philosopher and mathematician. He based De Homine on the concept of a human machine made by God to be almost identical to a real person. This meant he could explain the body mechanically without being restr- icted by contemporary religion and physiology.
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