Let us again remind the reader that evolution means, first of all, continuity. The law of evolution, although it doubtless means much more, means, first of all, a law of continuity, or causal relation throughout Nature. It means that, alike in every department of Nature, each state or condition grew naturally out of the immediately preceding. In a word, it means that, in the course of Nature, nothing appears suddenly and without natural cause, but, on the contrary, everything is the natural and usually the gradual outcome of a previous condition. This is now admitted by every one in regard to nearly everything: evolutionists apply it to the whole course of Nature. I said this is now admitted by every one in regard to nearly everything; but this has not always been so. The world has come to its present position on this subject only by a very gradual process. Let us then trace rapidly the history of the gradual change, for it will prepare us for much that follows.

There was a time (and that not many decades ago) when all things, the origin of which transcends our ordinary experience, were supposed to have originated suddenly and without natural process—to have been made at once, out of hand. There was a time when, for example, mountains were supposed to have been made at once, with all their diversified forms, of beetling cliffs and thundering waterfalls, or gentle slopes and smiling valleys, just as we now find them.