As for the instinct to mutilate, that is as easily accounted for as any other inherited habit, whether of man to mutilate cattle, or of ants to make slaves, or of birds to make their nests. I can see no way of accounting for the existence of any one of these instincts, except on the supposition that they have arisen gradually, through perceptions of power and need on the part of the animal which exhibits them—these two perceptions advancing hand in hand from generation to generation, and being accumulated in time and in the common course of nature. I have already sufficiently guarded against being supposed to maintain that very long before an instinct or structure was developed, the creature descried it in the far future, and made towards it. We do not observe this to be the manner of human progress. Our mechanical inventions, which, as I ventured to say in “Erewhon,” through the mouth of the second professor, are really nothing but extra-corporaneous limbs—a wooden leg being nothing but a bad kind of flesh leg, and a flesh leg being only a much better kind of wooden leg than any creature could be expected to manufacture introspectively and consciously—our mechanical inventions have almost invariably grown up from small beginnings, and without any very distant foresight on the part of the inventors. When Watt perfected the steam engine, he did not, it seems, foresee the locomotive, much less would any one expect a savage to invent a steam engine. A child breathes automatically, because it has learnt to breathe little by little, and has now breathed for an incalculable length of time; but it cannot open oysters at all, nor even conceive the idea of opening oysters for two or three years after it is born, for the simple reason that this lesson is one which it is only beginning to learn. All I maintain is, that, give a child as many generations of practice in opening oysters as it has had in breathing or sucking, and it would on being born, turn to the oyster-knife no less naturally than to the breast. We observe that among certain families of men there has been a tendency to vary in the direction of the use and development of machinery; and that in a certain still smaller number of families, there seems to be an almost infinitely great capacity for varying and inventing still further, whether socially or mechanically; while other families, and perhaps the greater number, reach a certain point and stop; but we also observe that not even the most inventive races ever see very far ahead. I suppose the progress of plants and animals to be exactly analogous to this.