 Mill takes it for granted that individuals act rationally in their pursuit of wealth and luxury and avoidance of labor, rather than in a disjointed or erratic way, but he has no theory of consumption, or explicit theory of rational economic choice, and his theory of resource allocation is rather thin. These gaps were gradually filled during the so-called neoclassical or marginalist revolution, which linked choice of some object of consumption (and its price) not to its total utility but to its marginal utility. For example, water is obviously extremely useful, but in much of the world it is plentiful enough that another glass more or less matters little to an agent. So water is cheap. Early “neoclassical” economists such as William Stanley Jevons held that agents make consumption choices so as to maximize their own happiness (1871). This implies that they distribute their expenditures so that a dollar’s worth of water or porridge or upholstery makes the same contribution to their happiness. The “marginal utility” of a dollar’s worth of each good is the same.