=Labour as the Common Third.=—A famous theory says that value expresses and measures the more or less of labour “embodied” in goods—the labour involved in the getting or making of goods. This, however, involves the idea of a Unit of Labour, _i.e._, it assumes the possibility of bringing all labour to a common expression—a previous equation. This difficulty seems insuperable, even when we look only at one side of the primitive equation: can any labour be more different in amount, intensity, and quality than that which gets gold? Suppose this overcome, and suppose the similar difficulty of equating the various labours involved in getting oxen overcome, what common quality measures these two sets of labours? When, finally, one tries to weigh head labour against hand labour, _except by the price paid for their results_, the full impossibility stands revealed. But, of course, to bring different labours to an equality by referring to the price paid for their results, is to beg the whole question. Assume that things are valuable and variously valuable, and one may pronounce that the labour spent on them will be correspondingly valuable; but the previous question is—Why are the products so variously valued? The hold which the Labour Theory took in last century can be explained only by its introduction of a moral idea making results (prices) depend on that which makes and elevates man, namely, Labour. But it certainly would make Value something very different from Human Valuation. (Note in passing that this theory is not to be confounded with the Cost of Production theory, which, indeed, is the other—the Supply—side of the true theory.) =Life as the Common Third.=—When Adam Smith said that water had great value in use, and diamonds scarcely any, he suggested life as the common third. It might, indeed, be possible to draw out a “natural order” of values—a hierarchy of things according to their power of sustaining an average human life. An animal or a Crusoe might value things in this way. It is evident that in prehistoric times the ox was adopted as the standard because of its measurable potentiality in this respect. But, in any community that we know, “life” is too complex to afford a basis; not only does “living” become intellectual, moral, æsthetic, but goods naturally availing to life, becoming plentiful, notoriously lose their value. This, however, suggests the true answer.