Let us—­to go into particulars—­suppose that the sole desire which moves exceptional men to devote their capacities to the augmentation of their country’s wealth is the desire to join a class which, whether idle or active otherwise—­whether devoted to mere pleasure or to philanthropy, or an enlightened patronage of the arts, or to speculative thought and study—­is itself in an economic sense altogether unproductive.  In order to join such a class, and to work with a view of joining it, society must be so organised that such a class can exist; and the fact of its existence constitutes the main moral magnet which, on our present hypotheses, is permanently essential to the development of the highest economic activity.  Such being the case, then, the following conclusion reveals itself, which, although it may seem paradoxical, will be found on reflection to be self-evident—­the conclusion namely, that a class which, if considered by itself, is absolutely non-productive, may, when taken in connection with the social system as a whole, be an essential and cardinal factor in the working machinery of production, constituting, as it would do by the mere fact of its existence, the charged electric accumulator by which the machinery is kept in motion; just as the mere existence of men, seen to be secure in their possession of the prizes of past lotteries, is the magnet which alone can make other men buy tickets for the lotteries of the future.

I have given this case as an assumption; but it is not an assumption only.  The desire for wealth as a means of living in absolute idleness is probably confined, as a fact, in all countries to a few.  In America especially it is a matter for surprise to strangers that men who have made fortune beyond the possibilities of pleasurable expenditure so rarely retire on them to cultivate the pursuits of leisure.  But even in America, if they do not value leisure for themselves, they value it for their women, to whom, there as in all countries, four-fifths of the charm and excitement of private life are due; and the sustained possibility of leisure, even if not the enjoyment of it—­a possibility which can rest only on a basis of sustained fortunes—­is the main advantage which, in all civilised countries, gives wealth its meaning for those who already possess it, and its charm for those who are, in order to possess it, exerting at any given moment their energies and their intellect in producing it.

The source of such sustained fortunes, in their distinctively modern form, is, as we have seen already, such and such forces of nature, which, captured and embodied in machines and other appliances by the masters of science and men of executive energy, and subsequently directed by other men of cognate talents, supplement the efficiency of ordinary human labour, thus yielding the surplus of which modern fortunes are a part, the remainder forming a fund which diffuses itself throughout the mass of the community.  That part of the surplus which constitutes such fortunes is interest; and now let us sum up what in this and the previous chapter our examination of the criticisms directed against interest has shown us.