In chapter 5 of his book More Heat Than Light (1989), Philip Mirowski mentions that the first neoclassical (W. S. Jevons, Leon Walras, Vilfredo Pareto, and Irving Fisher, but with the notable exception of Carl Menger) all referred to the analogy between their formulations and those of the physics of their day. Then he asserts, going beyond their statements on this matter, that the early neoclassical model was purely an analogical transposition of the model of the field theory of physics of the 1860s, which he calls “protoenergetics.” The latter implies a subject matter that is a mechanics of equilibrium and of reversible phenomena, and in which there is no question of the appearance of the notion of entropy.