There is certainly one limit which the increase of no organic being can exceed: the limit of the necessary means of subsistence. But, so far as the human race is concerned, this notion is somewhat more extensive, inasmuch as it embraces besides food, also clothing, shelter, fuel, and a great many other goods which are not, indeed, necessary to life, but which are so considered.[239-1] We may illustrate the matter by a simple example in the rule of division. If we take the aggregate of the means of subsistence as a dividend, the number of mankind as divisor; then the average share of each is the quotient. Where two of these quantities are given, the third may be found. Only when the dividend has largely increased can the divisor and quotient increase at the same time (prosperous increase of population). If, however, the quotient remains unchanged, the increase of the divisor can take place only at the expense of the quotient (proletarian increase of population).[239-2] Hence it is to be expected that the quantity of the means of subsistence being given and also the requirement of each individual, the number of births and the number of deaths should condition each other. Where, for instance, the number of church livings has not been increased, only as many candidates can marry as clergymen who held such livings have died. The greater the average age of the latter is, the later do the former marry, in the average, and _vice versa_. And so, in the case of whole nations, when their economic consumption and production remain unaltered.[239-3] A basin entirely filled with water can be made to contain more only in case it is either increased itself, or a means is found to compress its contents. Otherwise as much must flow out on the one side as is poured in on the other. And so, everything else remaining stationary, the fruitfulness of marriages must, at least in the long run, be in the inverse ratio of their frequency. (See § 247.)[239-4] [239-5] [Footnote 239-1: When it is known that, in the Hebrides, one-third of all the labor of the people has to be employed in procuring combustible material (_McCulloch_, Statist. Account, I, 319), it will no longer excite surprise that, according to Scotch statistics, some parishes increase in population after coal has been found in them, and others decrease when their turf-beds are exhausted.] [Footnote 239-2: Compare _Isaias_, 9:3. According to _Courcelle-Seneuil_, Traité théorique et pratique d'Economie politique, I, 1858, the _chiffre nécessaire de la population égal à la somme des revenus de la société diminuée de la somme des inégalités de consommation et divisée par le minimum de consommation_: P=(R-J)/M.]