To write everything about nothing, or to write nothing about everything: this is the problem. (Anonym, circa 1996-97) The first idea to write a book on M athematical Economics, more or less ordered in a historical sequence, occurred to me in 1995, when I was asked, by Istituto delta Enciclopedia Italiana, to write the entry "Storia dell'economia 1 2 matematica", for the collective work "Storia deI XX Secolo". I thought that it would be interesting...