In the writings of Aristotle, we find a much richer source for a history of Greek economic thought. Though no extant work of his is devoted to economics, he left a multitude of writings on diverse subjects, as a monument to his wonderful versatility and tireless industry.[517] Of these, the _Politics_ and the _Ethics_ are especially fruitful in economic ideas, though, as in the case of Plato, such material is incidental to the main discussion. His general attitude toward wealth and some of its problems, we shall find to be often substantially in agreement with that of Plato. His economic vision was prejudiced by the same ethico-aristocratic spirit. Yet his practical, scientific mind caused him to deal with many economic questions more extensively, more directly, and more incisively than is true of any other Greek thinker. Caution must be observed, however, against reading into his statements more meaning than he purposed to convey. He was not the creator of the science of political economy,[518] though his apprehension of many of the chief concepts of economics was probably clearer than has often been admitted by modern economists.[519] At the very threshold of economic speculation, Aristotle advanced beyond Plato and Xenophon, in that he perceived the fallacy in the confusion of household and public economy. He saw that they differed, not only in size or numbers, but in essential type.[520] In his later discussion of wealth, however, he overlooked his distinction, and fell into the old Greek confusion. VALUE The extent of Aristotle’s contribution to the theory of value has been very diversely estimated.[521] In a classic passage of the _Politics_, he distinguishes between the two uses of an object, the direct use for which it was produced, and the indirect as an article for exchange.[522] This has often been heralded as an anticipation of Adam Smith’s distinctions between value in use and value in exchange.[523] Such an interpretation, however, is hardly warranted.[524] The entire emphasis of Aristotle in the passage is upon use rather than upon value. The exchange use is declared subordinate, and the context shows that the purport of the statement is to teach the uneconomic doctrine that exchange (μεταβλητική) is an artificial use, especially when pursued for gain. Moreover, the passage fails to develop the definition further by distinguishing between economic utilities that involve a cost of production, and other necessities that are devoid of exchange value because of their universality.[525] Need is recognized as an element in exchange value,[526] but it is not differentiated from economic demand that has the means to purchase. All that can safely be said of this statement of Aristotle, therefore, is that he accidentally hit upon a basal distinction, which, had it been his purpose, he might have used as starting-point for the development of the modern theory of value.