And I believe that this will be felt as reasonable by the great majority of my readers. I believe that nine fairly intelligent and observant men out of ten, if they were asked which they thought most likely to have been the main cause of the development of the various phases either of structure or instinct which we see around us, namely—sense of need, or even whim, and hence occasional discovery, helped by an occasional piece of good luck, communicated, it may be, and generally adopted, long practised, remembered by offspring, modified by changed surroundings, and accumulated in the course of time—or, the accumulation of small divergent, indefinite, and perfectly unintelligent variations, preserved through the survival of their possessor in the struggle for existence, and hence in time leading to wide differences from the original type—would answer in favour of the former alternative; and if for no other cause yet for this—that in the human race, which we are best able to watch, and between which and the lower animals no difference in kind will, I think, be supposed, but only in degree, we observe that progress must have an internal current setting in a definite direction, but whither we know not for very long beforehand; and that without such internal current there is stagnation. Our own progress—or variation—is due not to small, fortuitous inventions or modifications which have enabled their fortunate possessors to survive in times of difficulty, not, in fact, to strokes of luck (though these, of course, have had some effect—but not more, probably, than strokes of ill luck have counteracted) but to strokes of cunning—to a sense of need, and to study of the past and present which have given shrewd people a key with which to unlock the chambers of the future. Further, Mr. Darwin himself says (“Plants and Animals under Domestication,” ii. p. 237, ed. 1875):—