Macaulay has spoken as if the Platonic philosophy was totally unrelated to the material wants of men. This, however, is a mistake. It is true that, in the _Republic_, science is not regarded as an instrument for heaping up fresh luxuries, or for curing the diseases which luxury breeds; but only because its purpose is held to be the discovery of those conditions under which a healthy, happy, and virtuous race can best be reared. The art of the true statesman is to weave the web of life with perfect skill, to bring together those couples from whose union the noblest progeny shall issue; and it is only by mastering the laws of the physical universe that this art can be acquired. Plato knew no natural laws but those of mathematics and astronomy; consequently, he set far too much store on the times and seasons at which bride and bridegroom were to meet, and on the numerical ratios by which they were supposed to be determined. He even tells us about a mysterious formula for discovering the nuptial number, by which the ingenuity of commentators has been considerably exercised. The true laws by which marriage should be regulated among a civilised people have remained wrapped in still more impenetrable darkness. Whatever may be the best solution, it can hardly fail to differ in many respects from our present customs. It cannot be right that the most important act in the life of a human being should be determined by social ambition, by avarice, by vanity, by pique, or by accident—in a word, by the most contemptible impulses of which human nature is susceptible; nor is it to be expected that sexual selection will always necessitate the employment of insincerity, adulation, and bribery by one of the parties concerned, while fostering in the other credulity, egoism, jealousy, capriciousness, and petty tyranny—the very qualities which a wise training would have for its object to root out.[145] It seems difficult to reconcile views about marriage involving a recognition of the fact that mental and moral qualities are hereditarily transmitted, with the belief in metempsychosis elsewhere professed by Plato. But perhaps his adhesion to the latter doctrine is not to be taken very seriously. In imitation of the objective world, whose essential truth is half hidden and half disclosed by its phenomenal manifestations, he loves to present his speculative teaching under a mythical disguise; and so he may have chosen the old doctrine of transmigration as an apt expression for the unity and continuity of life. And, at worst, he would not be guilty of any greater inconsistency than is chargeable to those modern philosophers who, while they admit that mental qualities are inherited, hold each individual soul to be a separate and independent creation.