Where then is the truth of saying, that from the altered relation between corn and money we deduce no other relation? It is perfectly obvious that we _can_ deduce and _do_ deduce a great number of other most important relations; and, in fact, _do_ ascertain, though not with perfect accuracy, yet with a most desirable and useful approach to it, the degree of increase in the power of corn to command in exchange the mass of other commodities. On the other hand, from the diminished power of money in relation to corn, we _cannot_ infer that money has fallen nearly in the same proportion in relation to other commodities. If an ounce of silver will now command only half a bushel of wheat, instead of a whole bushel, we can by no means infer that an ounce of silver will therefore command only about half the quantity of labour, half the quantity of cloth, half the quantity of hardware, half the quantity of hats and shoes, and of all those commodities which are in their natural and ordinary state. To all these objects money will probably bear nearly the same relation as before. Where, then, is the truth of saying, that money would not be here discharging a particular function more than the other commodity? Broad, glaring, and incontrovertible facts show, that for short periods money _does_ perform the function of measuring the variations in the general power of purchasing possessed by the corn; but that the corn does _not_ measure the variations in the general power of purchasing possessed by the money. This is one of the instances of that extraordinary inattention to facts which, most unfortunately for the science of political economy, the professors of it have lately indulged themselves in. The author has said a great deal in good set phrase about the false analogy involved in the application of the term _measure_ to the value of commodities at different periods; and gravely states the difference between measuring length at different periods and measuring value. I was not aware that people were ignorant of this difference. As I said before, whenever mention is made of the value of a commodity at different periods, I have always thought that a reference has been intended either to its general power of purchasing, or to something calculated to express the estimation in which it was held at these different periods, founded on the state of its supply compared with the demand, or the elementary costs of its production.