desire to possess, and the difficulty of obtaining possession of the other. The causes which affect the desire to possess, and the difficulty of obtaining possession of any one commodity, may with propriety be denominated the intrinsic causes of its power of purchasing; because the more these causes increase, the greater power will the commodity possess of purchasing all those objects which continue to be obtained with the same facility. The causes which affect the desire to possess, and the difficulty of obtaining possession of all the different commodities with which the first commodity might be exchanged, may with propriety be denominated the extrinsic causes of its power of purchasing; because while the desire to possess, and the difficulty of obtaining possession of the first commodity remains precisely the same, its power of purchasing other commodities may vary in any degree, owing to the variations in the desire to possess, and the difficulty of obtaining possession of all the other commodities with which it might be exchanged, that is, owing to causes extrinsic to those which operate on the first commodity. Now it is obvious that these extrinsic causes must, from their nature, and the variety of commodities to which they would apply, be almost innumerable; and though it would certainly be desireable to have some measure of the power of purchasing the mass of commodities, or at least the principal necessaries and conveniences of life, as it would enable us to form an estimate of the wealth of those persons who were in possession of particular commodities, or of certain revenues in money, yet when we consider what such a measure implies, we must feel assured that no one object exists, or can be supposed to exist with such qualities as would fit it to become a standard measure of this kind. It would imply steadiness in the desire to possess, and the difficulty of obtaining possession, not merely of one object, but of a great variety of objects, which is contrary to all theory and experience. But even if such a measure were attainable, though
