The result is that, though reproduction is greatly slackened, evolution is greatly accelerated. The significance of sex, as Coulter puts it, "lies in the fact that it makes organic evolution more rapid and far more varied." It is scarcely necessary to emphasise that a highly important, and, indeed, essential aspect of this greater individuation is a higher survival value. The more complex and better equipped creature can meet and subdue difficulties and dangers to which the more lowly organised creature that came before--produced wholesale in a way which Nature seems now to look back on as cheap and nasty--succumbed helplessly without an effort. The idea of economy begins to assert itself in the world. It became clear in the course of evolution that it is better to produce really good and highly efficient organisms, at whatever cost, than to be content with cheap production on a wholesale scale. They allowed greater developmental progress to be made, and they lasted better. Even before man began it was proved in the animal world that the death-rate falls as the birth-rate falls. If we wish to realise the vast progress in method which has been made, even within the limits of the vertebrates to which we ourselves belong, we have but to compare with the lowly herring, already cited, the highly evolved elephant. The herring multiplies with enormous rapidity and on a vast scale, and it possesses a very small brain, and is almost totally unequipped to grapple with the special difficulties of its life, to which it succumbs on a wholesale scale. A single elephant is carried for about two years in his mother's womb, and is carefully guarded by her for many years after birth; he possesses a large brain; his muscular system is as remarkable for its delicacy as for its power and is guided by the most sensitive perceptions. He is fully equipped for all the dangers of his life, save for those which have been introduced by the subtle devilry of modern man, and though a single pair of elephants produces so few offspring, yet their high cost is justified, for each of them has a reasonable chance of surviving to old age. The contrast from the point of view of reproduction of the herring and the elephant, the low vertebrate and the high vertebrate, well illustrates the tendency of evolution. It clearly brings before us the difference between Nature's earlier and later methods, the ever growing preference for quality of offspring over quantity. It has been necessary to touch on the wider aspects of reproduction in Nature, even when our main concern is with particular aspects of reproduction in man, for unless we understand the progressive tendency of reproduction in Nature, we shall probably fail to understand it in man. With these preliminary observations, we may now take up the question as it affects man.