Further, seeing it is not enough to the sustentation of a commonwealth, that every man have a propriety in a portion of land, or in some few commodities, or a natural property in some useful art, and there is no art in the world, but is necessary either for the being or well-being almost of every particular man; it is necessary that men distribute that which they can spare, and transfer their propriety therein, mutually one to another by exchange and mutual contract. And therefore it belongeth to the commonwealth, that is to say, to the sovereign, to appoint in what manner all kinds of contract between subjects, as buying, selling, exchanging, borrowing, lending, letting and taking to hire, are to be made; and by what words and signs they shall be understood for valid. And for the matter and distribution of the nourishment, to the several members of the commonwealth, thus much, considering the model of the whole work, is sufficient.
By concoction I understand the reducing of all commodities which are not presently consumed, but reserved for nourishment in time to come, to something of equal value, and withal so portable as not to hinder the motion of men from place to place; to the end a man may have in what place soever such nourishment as the place affordeth. And this is nothing else but gold, and silver, and money. For gold and silver, being, as it happens, almost in all countries of the world highly valued, is a commodious measure of the value of all things else between nations; and money, of what matter soever coined by the sovereign of a commonwealth, is a sufficient measure of the value of all things else between the subjects of that commonwealth. By the means of which measures all commodities, movable and immovable, are made to accompany a man to all places of his resort, within and without the place of his ordinary residence; and the same passeth from man to man within the commonwealth; and goes round about, nourishing as it passeth every part thereof; insomuch as this concoction is as it were the sanguification of the commonwealth; for natural blood is in like manner made of the fruits of the earth, and circulating, nourisheth by the way every member of the body of man.