Any boy with a turning-lathe can to-day make a model steam-engine, and no one will contend that such a model was not made by himself, on the ground that it could not have been made either by him or by anybody unless Watt, with his exceptional genius, had invented steam as a motive-power.
One might as well contend that a savage does not really light his own fire, on the ground that the art of kindling wood was found out by Prometheus, and that no one, except for him, would have had any fires at all.

The truth is, it will be said, that in such cases as these the powers of the exceptional man, originally confined to himself, are, when his invention is once in practical operation, naturally shared by his fellows, who can only be restrained from using them by artificial devices such as patents--these devices being at best, from a moral point of view, devices by which one man who has given a cheque to another man steals back half the money as soon as the cheque is cashed.
Now, both these arguments, so far as they go, are true; but neither has any bearing on the problem which is now before us.

That problem arises--let me observe once more--out of the assumption that, as a matter of justice, every man has a right to the products of all such forces as are his own; whence it follows that nobody has a right to the products of any forces which are not definitely in himself.

Let us take, then, the latter of the above arguments first.

It would doubtless be absurd to contend, were Prometheus alive to-day, that because he invented the art of striking fire from flints he ought to be paid a tribute by every savage who boiled a kettle; for the savage can strike a flint as well as Prometheus himself could.