Chapter IV. is the VALUE OF A LOT OF PLEASURE OR PAIN, HOW TO BE MEASURED. A pleasure or a pain is determined to be greater or less according to (1) its _intensity_, (2) its _duration_, (3) its _certainty_ or _uncertainty_, (4) its _propinquity_ or _remoteness_; all which are obvious distinctions. To these are to be added (5) its _fecundity_, or the chance it has of being followed by other sensations of its own kind; that is pleasures if it be pleasure, pains if it be pain. Finally (6) its _purity_, or the chance of its being unmixed with the opposite kind; a pure pleasure has no mixture of pain. All the six properties apply to the case of an individual person; where a plurality are concerned, a new item is present, (7) the _extent_, or the number of persons affected. These properties exhaust the meaning of the terms expressing good and evil; on the one side, happiness, convenience, advantage, benefit, emolument, profit, &c.; and, on the other, unhappiness, inconvenience, disadvantage, loss, mischief, and the like. Next follows, in Chapter V., a classified enumeration of PLEASURES AND PAINS. In a system undertaking to base all Moral and Political action on the production of happiness, such a classification is obviously required. The author professes to have grounded it on an analysis of human nature, which analysis itself, however, as being too metaphysical, he withholds. The simple pleasures are:--1. The pleasures of sense. 2. The pleasures of wealth. 3. The pleasures of skill. 4. The pleasures of amity. 5. The pleasures of a good name. 6. The pleasures of power. 7. The pleasures of piety. 8. The pleasures of benevolence. 9. The pleasures of malevolence. 10. The pleasures of memory. 11. The pleasures of imagination. 12. The pleasures of expectation. 13. The pleasures dependent on association. 14. The pleasures of relief. The simple pains are:--1. The pains of privation. 2. The pains of the senses. 3. The pains of awkwardness. 4. The pains of enmity. 5. The pains of an ill name. 6. The pains of piety. 7. The pains of benevolence. 8. The pains of malevolence. 9. The pains of the memory. 10. The pains of the imagination. 11. The pains of expectation. 12. The pains dependent on association. We need not quote his detailed subdivision and illustration of these. At the close, he marks the important difference between _self-regarding_ and _extra-regarding_; the last being those of benevolence and of malevolence.