Thus there are actually at all times producers and dealers, of all, or nearly all classes, whose capital is lying partially idle, because they have not found the means of fulfilling the condition which the division of labour renders indispensable to the full employment of capital,--viz., that of exchanging their products with each other. If these persons could find one another out, they could mutually relieve each other from this disadvantage. Any two shopkeepers, in insufficient employment, who agreed to deal at each other's shops so long as they could there purchase articles of as good a quality as elsewhere, and at as low a price, would render the nation a service. It may be said that they must previously have dealt, to the same amount, with some other dealers; but this is erroneous, since they could only have obtained the means of purchasing by being previously enabled to sell. By their compact, each would gain a customer, who would call his capital into fuller employment; each therefore would obtain an increased produce; and they would thus be enabled to become better customers to each other than they could be to third parties. It is obvious that every dealer who has not business sufficient fully to employ his capital (which is the case with all dealers when they commence business, and with many to the end of their lives), is in this predicament simply for want of some one with whom to exchange his commodities; and as there are such persons to about the same degree probably in all trades, it is evident that if these persons sought one another out, they have their remedy in their own hands, and by each other's assistance might bring their capital into more full employment. We are now qualified to define the exact nature of the benefit which a producer or dealer derives from the acquisition of a new customer. It is as follows:-- 1. If any part of his own capital was locked up in the form of unsold goods, producing (for a longer period or a shorter) nothing at all; a portion of this is called into greater activity, and becomes more constantly productive. But to this we must add some further advantages. 2. If the additional demand exceeds what can be supplied by setting at liberty the capital which exists in the state of unsold goods; and if the dealer has additional resources, which were productively invested (in the public funds, for instance), but not in his own trade; he is enabled to obtain, on a portion of these, not mere interest, but profit, and so to gain that difference between the rate of profit and the rate of interest, which may be considered as "wages of superintendance."