Which custom of barter is still preserved amongst many barbarous nations, who procure one necessary with another, but never sell anything; as giving and receiving wine for corn and the like. This sort of barter is not contradictory to nature, nor is it any species of money-getting; but is necessary in procuring that subsistence which is so consonant thereunto.
But this barter introduced the use of money, as might be expected; for a convenient place from whence to import what you wanted, or to export what you had a surplus of, being often at a great distance, money necessarily made its way into commerce; for it is not everything which is naturally most useful that is easiest of carriage; for which reason they invented something to exchange with each other which they should mutually give and take, that being really valuable itself, should have the additional advantage of being of easy conveyance, for the purposes of life, as iron and silver, or anything else of the same nature: and this at first passed in value simply according to its weight or size; but in process of time it had a certain stamp, to save the trouble of weighing, which stamp expressed its value. [1257b]
Money then being established as the necessary medium of exchange, another species of money-getting soon took place, namely, by buying and selling, at probably first in a simple manner, afterwards with more skill and experience, where and how the greatest profits might be made. For which reason the art of money-getting seems to be chiefly conversant about trade, and the business of it to be able to tell where the greatest profits can be made, being the means of procuring abundance of wealth and possessions: and thus wealth is very often supposed to consist in the quantity of money which any one possesses, as this is the medium by which all trade is conducted and a fortune made, others again regard it as of no value, as being of none by nature, but arbitrarily made so by compact; so that if those who use it should alter their sentiments, it