A significant feature of John Stuart Mill's moral theory is the introduction of qualitative differences as relevant to the comparative value of pleasures. Despite its significance, Mill presents his doctrine of qualities of pleasures in only a few paragraphs in the second chapter of Utilitarianism, where he begins the brief discussion by saying:
utilitarian writers in general have placed the superiority of mental over bodily pleasures chiefly … in their circumstantial advantages rather than in their intrinsic nature.… [B]ut they might have taken the … higher ground with entire consistency. It is quite compatible with the principle of utility to recognize the fact, that some kinds of pleasure are more desirable and more valuable than others. It would be absurd that while, in estimating all other things, quality is considered as well as quantity, the estimation of pleasures should be supposed to depend on quantity alone (U, II, 4).