Peerages, it is true, often become extinct. But it is quite clear, from what we have stated, that this is not because peeresses are barren. There is no difficulty in discovering what the causes really are. In the first place, most of the titles of our nobles are limited to heirs male; so that, though the average fecundity of a noble marriage is upwards of five, yet, for the purpose of keeping up a peerage, it cannot be reckoned at much more than two and a half. Secondly, though the peers are, as Mr. Sadler says, a marrying class, the younger sons of peers are decidedly not a marrying class; so that a peer, though he has at least as great a chance of having a son as his neighbours, has less chance than they of having a collateral heir. We have now disposed, we think, of Mr. Sadler’s principle of population. Our readers must, by this time, be pretty well satisfied as to his qualifications for setting up theories of his own. We will, therefore, present them with a few instances of the skill and fairness which he shows when he undertakes to null down the theories of other men. The doctrine {244}of Mr. Malthus, that population, if not checked by want, by vice, by excessive mortality, or by the prudent self-denial of individuals, would increase in a geometric progression, is, in Mr. Sadler’s opinion, at once false and atrocious. “It may at once be denied,” says he, “that human increase proceeds geometrically; and for this simple but decisive reason, that the existence of a geometrical ratio of increase in the works of nature, is neither true nor possible. It would fling into utter confusion all order, time, magnitude, and space.” This is as curious a specimen of reasoning as any that has been offered to the world since the days when theories were founded on the principle that nature abhors a vacuum. We proceed a few pages farther, however; and we then find that geometric progression is unnatural only in those cases in which Mr. Malthus conceives that it exists; and that, in all cases in which Mr. Malthus denies the existence of a geometric ratio, nature changes sides, and adopts that ratio as the rule of increase. Mr. Malthus holds that subsistence will increase only in an arithmetical ratio. “As far as nature has to do with the question,” says Mr. Sadler, “men might, for instance, plant twice the number of peas, and breed from a double number of the same animals, with equal prospect of their multiplication.” Now, if Mr. Sadler thinks that, as far as nature is concerned, four sheep will double as fast as two, and eight as fast as four, how can he deny that the geometrical ratio of increase does exist in the works of nature? Or has he a definition of his own for geometrical progression, as well as for inverse proportion?