Chapter CIII: Section CII: Demand

The purchaser in his demand is wont to consider principally the value in use of a commodity, according as it, in a higher or lower degree, ministers to a necessary want, to a decency or to a luxury. The difference of opinion as to which of these categories any given want belongs depends not only on the nature of the country and the customs of its people, but, for the most part, also, on the prejudices of class and on personal individuality.(613) A reasonable man will employ only the surplus of the first class in the satisfaction of wants of the second, and again only the surplus of the second in the satisfaction of wants of the third.(614)

If the value in use of a commodity rises or falls, and surrounding circumstances remain unchanged, its price also rises or falls.(615)(616)