Short answers, pulled from the story.
Jean-Baptiste Say is best known for Say's law, also called the law of markets, which holds that supply constitutes its own demand. He popularized the theory in his 1803 work the Traité d'économie politique, though scholars disagree on whether he was the first to articulate it.
Say was one of the first economists to study entrepreneurship systematically. He described entrepreneurs as intermediaries who combine land, capital, and labor to meet consumer demand, and argued their income was a form of high wages paid for skills and expert knowledge, a view that distinguished his theory from Joseph Schumpeter's later emphasis on risk-based profit.
Jean-Baptiste Say was born in Lyon on the 5th of January 1767. He died in Paris on the 15th of November 1832 and was buried in Père Lachaise Cemetery.
After Napoleon removed him from the Tribunat in 1804 for refusing to compromise his views, Say turned to industry. He established a cotton-spinning mill at Auchy-lès-Hesdin in the Pas de Calais that employed some 400-500 people, mostly women and children.
John Maynard Keynes coined the phrase "supply creates its own demand" and used it as a critical summary of Say's law. Some economists who support Say's law have disputed Keynes's characterization, arguing the principle is more accurately stated as "production precedes consumption."
In 1819 a chair of industrial economy was established for Say at the Conservatoire des Arts et Métiers. In 1825 he joined the improvement council of the École spéciale de commerce et d'industrie. In 1831 he was appointed professor of political economy at the Collège de France.