MONEY As Plato was the first of extant Greek thinkers to grasp the principle of the division of labor, so he was the first to give any hint as to the origin of money. He states that it came into use by reason of the growth of necessary exchange, which in turn resulted from increased division of labor.[187] The function of money he defines somewhat indefinitely by the term “token of exchange,”[188] an expression suggestive of Ruskin’s definition “a ticket or token of right to goods.”[189] It seems to imply that money is not itself a commodity to be trafficked in. In the Laws, he specifies more clearly the functions of this symbol. It acts as a medium of exchange and as a measure of value.[190] The latter office is performed by reason of the fact that money is a common denominator of value, changing products from incommensurable (ἀσύμμετρον) and uneven (ἀνώμαλον) to commensurable and even.[191] Since Plato did not consider money to be a commodity to be bought and sold, and since he did not appreciate its productive function as representative capital, his theory of interest was superficial. His attitude toward it was somewhat similar to that of many people today toward speculation in futures in the stock market, as a practice contrary to public interest and policy. The application of the term τόκος to interest by Plato[192] and Aristotle, as though interest were the direct child of money, is probably only a punning etymology, and not intended seriously. It can therefore hardly be used, as it often is, to prove the superficiality of the theory of the Socratics. Plato, however, would have no money-making by usury,[193] nor indeed any loaning or credit at all, except as an act of friendship.[194] Such contracts should be made at the loaner’s own risk,[195] and held legal only as a punishment for breaking other contracts.[196] He calls the usurer a bee that inserts his sting, money, into his victims, thereby beggaring them and enriching himself.[197] Such strictures against interest were common in mediaeval Europe, reappeared in Ruskin,[198] and are implied in the present opposition, in some quarters, to so-called “unearned income.”[199] The motive in mediaeval times, however, was distinctively religious, and was also partly due to the absence of a developed capitalism. With Ruskin and modern theorists, on the other hand, the objection is, at bottom, socialistic. The motive of the Socratics was essentially moral and political.