Before passing from subjective or personal value, there remains for consideration one point, which is at once important in itself, and decisive against the old division of the total phenomena under discussion into value in use and value in exchange. To the subtle analysis of Böhm-Bawerk and Wieser we owe the recognition of _subjective_ exchange value, as distinct from the purely _objective_ exchange value which we have to consider in following chapters. Aristotle said that every good had two uses, “both belonging to the thing as such”: similarly we say that every good has two subjective importances, that which it can directly afford, and that which the things got in exchange for it can afford. A little reflection will convince us that subjective value contains these two distinct branches, use value and exchange value. It may occasionally suit the economist, for purposes of illustration, to discuss the economy of a Crusoe—particularly in problems of production where the essential features of society, as at once a producing and consuming body, are obscured by the division of labour—but, in the simplest form of society known to experience, there is always some barter or exchange of goods. But, wherever this is the case, every good acquires a second possible value as an exchange form of other goods, or a potentiality of obtaining other goods. In the organism called society, each man becomes—at least potentially—richer or poorer with the increase or decrease of its wealth. Some part of our neighbour’s goods becomes available for the satisfaction of our want whenever exchange becomes possible between us, inasmuch as the actual existence of his surplus—not to mention his enjoyment of it—depends on our co-operation. Thus the goods which were first valuable to us personally, as possible satisfaction of our want, get a secondary value. Every good becomes potentially a number of other goods, and the range of our possible satisfactions becomes by so much widened. The presence of exchange, in short, gives us a choice of values.