DAVID RICARDO, one of the most celebrated economists of modern times, was born in London, April 19th, 1772. His father, a stock broker of Hebrew ancestry, wished to educate his son for business, but Ricardo preferred science, and his admiration for Adam Smith made him a political economist. His “Principles of Political Economy and Taxation” appeared in 1817 and soon took rank as one of the notable books of the century. It was preceded and followed by a long list of essays, treatises, and elaborate works on similar topics. Ricardo’s theory that exchange value is determined by labor cost has been taken into account by all his successors, as has also his theory of rent. He died September 11th, 1823.