It is a mistake, then, to take the view adopted by a previous correspondent of this paper, to consider the machines as identities, to animalise them and to anticipate their final triumph over mankind. They are to be regarded as the mode of development by which human organism is most especially advancing, and every fresh invention is to be considered as an additional member of the resources of the human body. Herein lies the fundamental difference between man and his inferiors. As regard his flesh and blood, his senses, appetites, and affections, the difference is one of degree rather than of kind, but in the deliberate invention of such unity of limbs as is exemplified by the railway train—that seven-leagued foot which five hundred may own at once—he stands quite alone. In confirmation of the views concerning mechanism which we have been advocating above, it must be remembered that men are not merely the children of their parents, but they are begotten of the institutions of the state of the mechanical sciences under which they are born and bred. These things have made us what we are. We are children of the plough, the spade, and the ship; we are children of the extended liberty and knowledge which the printing press has diffused. Our ancestors added these things to their previously existing members; the new limbs were preserved by natural selection and incorporated into human society; they descended with modifications, and hence proceeds the difference between our ancestors and ourselves. By the institutions and state of science under which a man is born it is determined whether he shall have the limbs of an Australian savage or those of a nineteenth-century Englishman. The former is supplemented with little save a rug and a javelin; the latter varies his physique with the changes of the season, with age and with advancing or decreasing wealth. If it is wet he is furnished with an organ which is called an umbrella and which seems designed for the purpose of protecting either his clothes or his lungs from the injurious effects of rain. His watch is of more importance to him than a good deal of his hair, at any rate than of his whiskers; besides this he carries a knife and generally a pencil case. His memory goes in a pocket-book. He grows more complex as he becomes older and he will then be seen with a pair of spectacles, perhaps also with false teeth and a wig; but, if he be a really well-developed specimen of the race, he will be furnished with a large box upon wheels, two horses, and a coachman.