Folks, The person who first drew a supply and demand diagram with P on the vertical axis was Karl Heinrich Rau, not "Johannes" Rau, as I mistakenly wrote earlier. It was in the second edition of his Grundzatze der Volkwirthschastlehre, published in 1841 (first edition, 1826). He was one of the German "proto-neoclassicals." A good source on them is Erich W. Streissler, "Rau, Hermann and Roscher: contributions of German economics around the middle of the nineteenth century," European Journal of the History of Economic Thought, September 2001, vol. 8, issue 3, pp. 311-331. Sorry about the incorrect first name. Barkley Rosser