With respect to the variations in value, of which every thing valuable is susceptible, if we could for a moment suppose that any substance possessed intrinsic and fixed value, so as to render an assumed quantity of it constantly, under all circumstances, of an equal value, then the degree of value of all things, ascertained by such a fixed standard, would vary according to the proportion betwixt the quantity of them and the demand for them, and every commodity would of course be subject to a variation in its value, from four different circumstances.