But this dismal creed does not discourage those who believe that the impulse that produces evolution is creative. They have observed the simple fact that the will to do anything can and does, at a certain pitch of intensity set up by conviction of its necessity, create and organize new tissue to do it with. To them therefore mankind is by no means played out yet. If the weight lifter, under the trivial stimulus of an athletic competition, can 'put up a muscle,' it seems reasonable to believe that an equally earnest and convinced philosopher could 'put up a brain.' Both are directions of vitality to a certain end. Evolution shews us this direction of vitality doing all sorts of things: providing the centipede with a hundred legs, and ridding the fish of any legs at all; building lungs and arms for the land and gills and fins for the sea; enabling the mammal to gestate its young inside its body, and the fowl to incubate hers outside it; offering us, we may say, our choice of any sort of bodily contrivance to maintain our activity and increase our resources. VOLUNTARY LONGEVITY Among other matters apparently changeable at will is the duration of individual life. Weismann, a very clever and suggestive biologist who was unhappily reduced to idiocy by Neo-Darwinism, pointed out that death is not an eternal condition of life, but an expedient introduced to provide for continual renewal without overcrowding. Now Circumstantial Selection does not account for natural death: it accounts only for the survival of species in which the individuals have sense enough to decay and die on purpose. But the individuals do not seem to have calculated very reasonably: nobody can explain why a parrot should live ten times as long as a dog, and a turtle be almost immortal. In the case of man, the operation has overshot its mark: men do not live long enough: they are, for all the purposes of high civilization, mere children when they die; and our Prime Ministers, though rated as mature, divide their time between the golf course and the Treasury Bench in parliament. Presumably, however, the same power that made this mistake can remedy it. If on opportunist grounds Man now fixes the term of his life at three score and ten years, he can equally fix it at three hundred, or three thousand, or even at the genuine Circumstantial Selection limit, which would be until a sooner-or-later-inevitable fatal accident makes an end of the individual. All that is necessary to make him extend his present span is that tremendous catastrophes such as the late war shall convince him of the necessity of at least outliving his taste for golf and cigars if the race is to be saved. This is not fantastic speculation: it is deductive biology, if there is such a science as biology. Here, then, is a stone that we have left unturned, and that may be worth turning. To make the suggestion more entertaining than it would be to most people in the form of a biological treatise, I have written