The Song of the Cell: An Exploration of Medicine and the New Human

by Siddhartha Mukherjee

For generations before Bernard and Cannon, physiologists had described animals as assemblages of machines, sums of dynamic parts. Muscles were motors; the lungs a pair of bellows, the heart a pump. Pulsing, swiveling, pumping; physiology’s emphasis was on movement, on actions, on work. Don’t just stand there, do something. Bernard inverted that logic. “La fixité du milieu intérieur est la condition de la vie libre, indépendante”: the constancy of the interior environment is the condition of free and independent life, Bernard wrote in 1878.23 In shifting physiology’s focus from action to the maintenance of fixity, Bernard changed our conception of how an organism’s body works. A major point of physiological “activity,” paradoxically, was to enable stasis. Don’t just do something, stand there.