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.
Plato’s other error concerning money, as above observed, was that it need possess no intrinsic value for domestic use. He looked upon gold and silver as causes of degeneration in state and individual,200 and would therefore have put a ban on them for use within the state.201 To his mind, a mere state fiat was sufficient to give currency and value.202 This doctrine has also often recurred in the history of economic thought, as in Ruskin and the Greenback party of a generation ago.203 The error, however, was not so grave in Plato’s case, for he, at least, recognized the need of the precious metals for international purposes.204 Moreover, in his proposed state of such limited extent, the problem would have been far