He has reckoned that he shall derive from this tool an advantage, which will allow him to restore it in its original condition, after having realized a profit from it.

As long as James does not use this capital himself, or for his own advantage--as long as he renounces the advantages which allow it to be restored to its original condition--he will have an incontestable right to have it restored, and that independently of interest.
Observe, besides, that if, as I believe I have shown, James, far from doing any harm to William, has done him a _service_ in lending him his plane for a year; for the same reason, he will do no harm to a second, a third, a fourth borrower, in the subsequent periods.

Hence you may understand, that the interest of a capital is as natural, as lawful, as useful, in the thousandth year, as in the first.

We may go still further.

It may happen, that James lends more than a single plane.