Evolution and Ethics joins two pieces Huxley printed together: the Romanes Lecture of 1893 and the longer Prolegomena he wrote in 1894 to introduce it. The whole essay sets out to remove what he calls a stumbling-block, the apparent paradox that human moral nature, although it grew out of nature, is necessarily at enmity with its parent. He treats that paradox as a plain truth that any ethical thinker must face.
He begins from a window looking out on the Sussex downs. Two thousand years ago the country there was in the state of nature: native grasses and gorse fighting one another for thin soil, frost, drought, and gales thinning their ranks, an unceasing struggle for existence settling which forms survive. This is the cosmic process. Its mark in the living world is competition, and its result is selection, the survival of the forms best adapted to current conditions and fittest only in that narrow respect.
Then Huxley walls off a small patch and makes it a garden. Inside, the native plants are cleared and chosen exotics are raised under conditions that could never occur in the wild. The garden is a work of art, and the moment the gardener stops tending it the weeds, frosts, and trespassers begin to take it back. Its principle is the opposite of the cosmic process: instead of letting the struggle run, the gardener removes the struggle by adjusting the conditions to suit the plants he wants. Huxley calls this the horticultural process and uses it as the model for human ethics.
Human society, on this view, is a garden and morality is the gardening. The ethical process, the growth of sympathy and conscience into law and custom, restrains the struggle for existence between people. It works against the cosmic principle, suppressing the very qualities that win in the wild. Huxley turns this against the social theorists of his day who invoked nature to justify letting the weak go under. The cosmic process, he insists, has no relation to moral ends, so imitating it is inconsistent with the first principles of ethics.
His conclusion is famous and blunt: the ethical progress of society depends not on imitating the cosmic process, nor on running away from it, but on combating it. He has no millennial hope. The nature born in us is the outcome of millions of years of training and will remain a tenacious enemy as long as the world lasts, and in the far future the cosmic process will resume its sway over the planet. Yet he holds that intelligence and organized will can modify the conditions of existence and curb the savagery in civilized people, so that we should set our hearts not on escaping pain but on diminishing the evil in and around us.