“What a new thing it is for a machine to feed at all!  The plough, the spade, and the cart must eat through man’s stomach; the fuel that sets them going must burn in the furnace of a man or of horses.  Man must consume bread and meat or he cannot dig; the bread and meat are the fuel which drive the spade.  If a plough be drawn by horses, the power is supplied by grass or beans or oats, which being burnt in the belly of the cattle give the power of working:  without this fuel the work would cease, as an engine would stop if its furnaces were to go out.

“A man of science has demonstrated ’that no animal has the power of originating mechanical energy, but that all the work done in its life by any animal, and all the heat that has been emitted from it, and the heat which would be obtained by burning the combustible matter which has been lost from its body during life, and by burning its body after death, make up altogether an exact equivalent to the heat which would be obtained by burning as much food as it has used during its life, and an amount of fuel which would generate as much heat as its body if burned immediately after death.’  I do not know how he has found this out, but he is a man of science—­how then can it be objected against the future vitality of the machines that they are, in their present infancy, at the beck and call of beings who are themselves incapable of originating mechanical energy?

“The main point, however, to be observed as affording cause for alarm is, that whereas animals were formerly the only stomachs of the machines, there are now many which have stomachs of their own, and consume their food themselves.  This is a great step towards their becoming, if not animate, yet something so near akin to it, as not to differ more widely from our own life than animals do from vegetables.  And though man should remain, in some respects, the higher creature, is not this in accordance with the practice of nature, which allows superiority in some things to animals which have, on the whole, been long surpassed?  Has she not allowed the ant and the bee to retain superiority over man in the organisation of their communities and social arrangements, the bird in traversing the air, the fish in swimming, the horse in strength and fleetness, and the dog in self-sacrifice?

“It is said by some with whom I have conversed upon this subject, that the machines can never be developed into animate or quasi-animate existences, inasmuch as they have no reproductive system, nor seem ever likely to possess one.  If this be taken to mean that they cannot marry, and that we are never likely to see a fertile union between two vapour-engines with the young ones playing about the door of the shed, however greatly we might desire to do so, I will readily grant it.  But the objection is not a very profound one.  No one expects that all the features of the now existing organisations will be absolutely repeated in an entirely new class of life.  The reproductive system of animals differs widely from that of plants, but both are reproductive systems.  Has nature exhausted her phases of this power?