Thus Whittington's cat, sent to a far country where cats are scarce and rats are plenty, returns in bales of goods and bags of gold.
Of course, labor is necessary to exchange, as it is to the utilization of the reproductive forces of nature, and the produce of exchange, as the produce of agriculture, is clearly the produce of labor; but yet, in the one case as in the other, there is a distinguishable force co-operating with that of labor, which makes it impossible to measure the result solely by the amount of labor expended, but renders the amount of capital and the time it is in use integral parts in the sum of forces. Capital aids labor in all of the different modes of production, but there is a distinction between the relations of the two in such modes of production as consist merely of changing the form or place of matter, as planing boards or mining coal; and such modes of production as avail themselves of the reproductive forces of nature, or of the power of increase arising from differences in the distribution of natural and human powers, such as the raising of grain or the exchange of ice for sugar. In production of the first kind, labor alone is the efficient cause; when labor stops, production stops. When the carpenter drops his plane as the sun sets, the increase of value, which he with his plane is producing, ceases until he begins his labor again the following morning. When the factory bell rings for closing, when the mine is shut down, production ends until work is resumed. The intervening time, so far as regards production, might as well be blotted out. The lapse of days, the change of seasons is no element in the production that depends solely upon the amount of labor expended. But in the other modes of production to which I have referred, and in which the part of labor may be likened to the operations of lumbermen who throw their logs into the stream, leaving it to the current to carry them to the
