Demand theory grew out of the revision of utilitarianism. The original, Benthamite program based on a naturalistic, hedonic interpretation of behavior was replaced by an abstract, subjectivist approach, a motivational mechanics. The implications expressed exclusively in observable quantities, prices, and incomes were developed in demand theory. The paper discusses major steps and consequences of the revision together with more recent partial revocations and attempts at reintroducing a naturalistic interpretation. The latter can be enhanced, it is argued, by integrating the (non-utilitarian) theory of wants, a long-standing, but currently much neglected, source of empirical reflections on the motivations of economic behavior.