This problem is closely analogous to that of the distribution of pleasures to those who compose the "greatest number" taken into account. There we were concerned with the shares allotted to individuals; here we are concerned with the shares assigned to the different parts of a single life. In the attempt to solve the problem, Bentham's criteria of intensity, certainty, purity, etc., might naturally be appealed to. 110. THE CALCULUS OF PLEASURES.--Nor are the problems which meet us less perplexing when we pass from questions of the distribution of pleasures to that of the calculus of pleasures. How are delights and miseries to be weighed, and reasonably balanced? (1) Men desire pleasure, and they desire to avoid pain. The two seem to be opposed. But men constantly accept pleasures which entail some suffering, and they avoid pains even at the expense of some pleasure. Are, however, pleasures and pains strictly commensurable? How much admixture of pain is called for to reduce the value of a pleasure to zero? and how much pleasure, added to a pain, will make the whole emotional state predominantly a pleasurable one? A disagreeable taste and an agreeable odor may be experienced together, but they cannot be treated as an algebraic sum. If we do so treat them, we seem to fall back upon the assumption that the mere fact that the heterogeneous complex is accepted or rejected is evidence that its ingredients have been measured and compared. This is an ungrounded assumption. (2) Undoubtedly men prefer intense pleasures to mild ones, and those long-continued to those which are fleeting. But what degree of intensity will overbalance what period of duration? Here, again, we appear to be without a unit of measure, both in the case of pleasures and of pains. (3) Obviously, he who would distribute pleasures with impartiality must take into consideration the natures and capacities of the recipients. All are not susceptible of pleasure in the same degree, nor are all capable of enjoying the same pleasures. It is small kindness to a cat to offer it hay; nor will the miser thank us for the opportunity to enjoy the pleasures of liberality. The gift which arouses deep emotion in one man, will leave another cold. The diversity of natures would make the calculus of pleasures, in any accurate sense of the expression, a most difficult problem, even if such a calculus were admissible in the case of a single individual. [Footnote: This difficulty has not been overlooked by the Utilitarian, see BENTHAM, _Principles of Morals and Legislation_, chapter vi.] III. THE DIFFICULTIES OF OTHER SCHOOLS.--It would be unjust to the utilitarian not to point out that those who advocate other doctrines must find some way of coping with the difficulties which embarrass him.