adaptations might occur within it, and to what excellence human nature in particular might arrive. Nor is it unlikely that before the cataclysm comes time will be afforded for more improvement than moral philosophy has ever dreamed of. For it is remarkable how inane and unimaginative Utopias have generally been. This possibility is not uninspiring and may help to console those who think the natural conditions of life are not conditions that a good life can be lived in. The possibility of essential progress is bound up with the tragic possibility that progress and human life should some day end together. If the present equilibrium of forces were eternal all adaptations to it would have already taken place and, while no essential catastrophe would need to be dreaded, no essential improvement could be hoped for in all eternity. I am not sure that a humanity such as we know, were it destined to exist for ever, would offer a more exhilarating prospect than a humanity having indefinite elasticity together with a precarious tenure of life. Mortality has its compensations: one is that all evils are transitory, another that better times may come.
Human nature, then, has for its core the substance of nature at large, and is one of its more complex formations. Its determination is progressive. It varies indefinitely in its historic manifestations and fades into what, as a matter of natural history, might no longer be termed human. At each moment it has