However, they are not to be treated as animals, but as rational men, in whom a proper usage may develop a certain degree of morality and ambition for good work.184
To be sure, his purpose is economic rather than ethical—to make the slaves satisfied with their lot, and thus better producers.185
He makes no mention of freedom as a reward for good behavior, though he elsewhere provides for the existence of freedmen in the state, and stipulates that they shall not become richer than their former masters.186
# 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.