Léon Walras
Notes
Léon Walras (1834–1910), French economist at Lausanne, the third independent originator of marginal utility theory (Elements of Pure Economics, 1874) and the founder of general equilibrium theory, the mathematical description of how all prices in an economy are determined together. The most mathematical of the three and the one whose work most directly underlies modern economics.
Wikipedia: https://en.wikipedia.org/wiki/L%C3%A9on_Walras