This is the reason why man is constantly stimulated to exercise foresight, in order to turn it to account. He has always in [p177] perspective a possible rise or fall of value,—a recompense for just and sagacious prevision, and chastisement when it is erroneous. And, observe, his success or failure coincides with the public good or the public detriment. If his foresight has been well directed, if he has made preparations beforehand to give society the benefit of services which are more in request, more appreciated, more efficacious, which supply more adequately wants which are deeply felt, he has contributed to diminish the scarcity, to augment the abundance, of that description of service, and to bring it within the reach of a greater number of persons at less expense. If, on the other hand, he is mistaken in his calculations for the future, he contributes, by his competition, to depress still farther those services for which there is little demand. He only effects, and at his own expense, a negative good,—he advertises the public that a certain description of wants no longer call for the exertion of much social activity, which activity must now take another direction, or go without recompense. This remarkable fact—that ‹value›, ‹incorporated› in a product, depends on the value of the kind of service to which it owes its origin—is of the very highest importance, not only because it demonstrates more and more clearly the theory that the principle of value resides in the service, but because it explains, easily and satisfactorily, phenomena which other systems regard as abnormal and exceptional. When once the product has been thrown upon the market of the world, do the general tendencies of society operate towards elevating or towards depressing its ‹value›? This is to ask whether the particular kind of services which have engendered this value are liable to become more or less appreciated, and better or worse remunerated. The one is as possible as the other, and it is this which opens an unlimited field to human foresight.