Claude Bernard wanted to be a playwright; a critic sent him to medicine
In 1834 a young druggist's assistant took his five-act tragedy to a Paris critic, who told him to study medicine instead. Claude Bernard went on to explain how the body keeps its inner conditions stable, an idea later named homeostasis, and France gave him the first public funeral ever granted to a scientist.
Bernard was born on 12 July 1813 in Saint-Julien, near Villefranche-sur-Saone, schooled by Jesuits and then briefly at college in Lyon before working in a pharmacy. A vaudeville comedy he wrote did well enough that he tried a tragedy about Arthur, Duke of Brittany. The critic Saint-Marc Girardin read it and steered him toward medicine. As an intern at the Hotel-Dieu in Paris he met the physiologist Francois Magendie, became his lab assistant at the College de France in 1841, and succeeded him as professor in 1855. His lab was famously a cellar, and his marriage in 1845 was arranged partly so that his wife's dowry could pay for experiments.
His discoveries reshaped physiology. He showed that pancreatic juice contains an enzyme that breaks fats into glycerol and fatty acids, overturning the view that the pancreas mattered little, and William Bayliss credited this work as a step toward discovering secretin, the first hormone isolated. He found that the liver manufactures sugar, advancing research on diabetes. In 1851 he noticed that cutting a nerve in the neck increased blood flow in parts of the head, uncovering nerves that widen and narrow blood vessels. In 1857 he described how carbon monoxide binds to haemoglobin.
His central idea was the milieu interieur, an internal environment that stays relatively independent of the outside world and compensates for its shortfalls. Walter Cannon later coined homeostasis for the principle. In his 1865 Introduction to the Study of Experimental Medicine, Bernard argued that theories are only hypotheses to be tested against facts, and criticised researchers who chose data to fit their beliefs.
His methods were bitterly contested. He championed animal vivisection, which appalled his wife and daughters; the couple separated in 1869 and his wife campaigned against the practice. George Hoggan, who spent four months in his laboratory, became a founder of the National Anti-Vivisection Society. Bernard died on 10 February 1878 and lies in Pere Lachaise Cemetery.
Source: Claude Bernard
