There is a certain economic and moral truth, also, in the attitude of Aristotle toward slavery, that, as Ruskin has observed,[671] higher civilization and culture must have a foundation of menial labor, and that the only justification of such a situation is in the assumption that some are naturally fitted for the higher, and some for the lower, sphere.[672] Such modern laborers are not technically slaves, but Aristotle would insist that they are in a still worse condition, since they are deprived of the humanizing and moralizing influences of a rational master. The plausibility of such a contention would be well illustrated by the wretched condition of multitudes of negroes after the Civil War, as also by the hopeless life of a large portion of the modern industrial army. Moreover, the economic slavery of many of the common toilers today is less justifiable than the domestic slavery advocated by Aristotle, for it too often means a life of indolence and self-indulgence for the masters, instead of that Greek leisure which gave opportunity for higher activity.[673] MONEY To the theory of money Aristotle makes a substantial contribution. He agrees with Plato that money found its origin in the growth of necessary exchange, which in turn resulted from an increased division of labor. Unlike Plato, however, he gives a detailed history of the development of money.[674] Before its invention, all exchange was by barter.[675] But with the growth of commerce, barter became difficult, and a common medium of exchange was agreed upon.[676] Something was chosen that was a commodity, having intrinsic value (ὁτῶν χρησίμων αὐτὸ ὄν) and that was easy to handle (εὐμεταχείριστον) in the business of life such as iron, silver, or other metal.[677] It was first uncoined, defined merely by size and weight.[678] Finally, to avoid the inconvenience, it was given a stamp (χαρακτήρ) representative of the quantity (σημεῖον τοῦ πόσου).[679] Thus arose the use of money as a convenience in necessary exchange, but once having arisen, it became the foundation of false finance and retail trade, which are pursued as a science of gain.[680] All this accords well with the facts as now accepted, yet how utterly different is Aristotle’s standpoint from that of the modern historian of economic institutions is revealed by his last statement, and indeed by the setting of the entire passage. His history of money is merely incidental to his purpose of showing that money is the parent and the very life of the false finance which he decries.