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.