Page:Principles of Political Economy Vol 2.djvu/167

Rh § 8. We have now arrived at what seems a law of International Values, of great simplicity and generality. But we have done so by setting out from a purely arbitrary hypothesis respecting the relation between demand and cheapness. We have assumed their relation to be fixed, though it is essentially variable. We have supposed that every increase of cheapness produces an exactly proportional extension of demand; in other words, that the same invariable value is laid out in a commodity whether it be cheap or dear; and the law which we have investigated holds good only on this hypothesis, or some other practically equivalent to it. Let us now, therefore, combine the two variable elements of the question, the variations of each of which we have considered separately. Let us suppose the relation between demand and cheapness to vary, and to become such as would prevent the rule of interchange laid down in the last theorem from satisfying the conditions of the Equation of International Demand. Let it be supposed, for instance, that the demand of England for linen is exactly proportional to the cheapness,