To a person, he says, considered _by himself_, the value of a pleasure or pain considered _by itself_, will be greater or less, according to the four following circumstances. 1. Its _intensity_. 2. Its _duration_. 3. Its _certainty_ or _uncertainty_. 4. Its _propinquity_ or _remoteness_. But when the value of any pleasure or pain is to be considered for the purpose of estimating the general tendency of the act, we have to take into account also, 5. The _fecundity_, or the chance it has of being followed by sensations of the same kind, that is, pleasures, if it be a pleasure; pains, if it be a pain. 6. Its _purity_, or the chance it has of _not_ being followed by sensations of the _opposite_ kind: that is, pains, if it be a pleasure; pleasures, if it be a pain. Finally, when we consider the interests of a number of persons, we must also estimate a pleasure or pain with reference to, 7. Its extent; that is the number of persons to whom it extends, or who are affected by it. Thus did Bentham clearly and explicitly lay the foundations of the moral and political sciences, and to impress these fundamental propositions on the memory he framed the following curious mnemonic lines, which may be quoted for the sake of their quaintness:-- "_Intense, long, certain, speedy, fruitful, pure_---- Such marks in pleasures and in pains endure. Such pleasures seek, if private be thy end: If it be public, wide let them _extend_. Such _pains_ avoid, whichever be thy view: If pains _must_ come, let them _extend_ to few." In all that Bentham says about pleasure and pain, there is not a word about the intrinsic superiority of one pleasure to another. He advocates our seeking _pure_ pleasures; but with him a pure pleasure was clearly defined as one not likely to be followed by feelings of the opposite kind; the pleasure of opium-eating, for instance, would be called impure, simply because it is likely to lead to bad health and consequent pain; if not so followed by evil consequences, the pleasure would be as pure as any other pleasure. With Bentham morality became, as it were, a question of the ledger and the balance-sheet; all feelings were reduced to the same denomination of value, and whenever we indulge in a little enjoyment, or endure a pain, the consequences in regard to subsequent enjoyment or suffering are to be inexorably scored for or against us, as the case may be. Our conduct must be judged wise or foolish according as, in the long-run, we find a favourable "hedonic" balance-sheet.