(1848-1923). Born in Paris, the son of a French marquis. Moved to Italy in 1852. Obtained high school diploma in July 1864, and published his first paper in 1866. Completed mathematics and engineering degrees by 1870. Founding member of the Adam Smith society. A liberal, with socialist leanings and a pacifist. Was an influential economist. Wrote a critique of Marx's theory of value; developed the idea of Pareto efficiency, developed Pareto's Law on wealth distribution, and was highly influential in the early theory of economic externalities. Also made fundamental contributions to the broader study of human society.