Walter Bradford Cannon (1871-1945) was an American physiologist, professor and chairman of the Department of Physiology at Harvard Medical School. He coined the term fight or flight response, and he expanded on Claude Bernard's concept of homeostasis. He popularized his theories in his book The Wisdom of the Body, first published in 1932. Cannon summarized his career by describing his focus at different ages: 26-40: digestion and the bismuth meal, 40-46: bodily effects of emotional excitement, 46-51: wound shock investigations, 51-59: stable states of the organism, 59-68: chemical mediation of nerve impulses and lastly, 68+: chemical sensitivity of nerve-isolated organs. He lived to be 73 and died of natural causes.