After all, God forbid that I should desire to set myself against the noblest attribute, the most beautiful virtue of man, self-control, command over his passions, moderation in his desires, contempt of show. I don’t say that he is to make himself a slave to this or that factitious want. I say that wants (taking a broad and general [p082] view of them as resulting from man’s mental and bodily constitution), combined with the power of habit, and the sense of dignity, are indefinitely expansible, because they spring from an inexhaustible source—namely, desire. Who should blame a rich man for being sober, for despising finery, for avoiding pomp and effeminacy? But are there not more elevated desires to which he may yield? Has the desire for instruction, for instance, any limits? To render service to his country, to encourage the arts, to disseminate useful ideas, to succour the distressed,—is there anything in these incompatible with the right use of riches? For the rest, whatever philosophers may think of it, human wants do not constitute a fixed immutable quantity. That is a certain, a universal fact, liable to no exception. The wants of the fourteenth century, whether with reference to food, or lodging, or instruction, were not at all the wants of ours, and we may safely predict that ours will not be the wants of our descendants. The same observation applies to all the elements of Political Economy—Wealth, Labour, Value, Services, etc.,—all participate in the extreme versatility of the principal subject, Man. Political Economy has not, like geometry or physics, the advantage of dealing with objects which can be weighed or measured. This is one of its difficulties to begin with, and it is a perpetual source of errors throughout; for when the human mind applies itself to a certain order of phenomena, it is naturally on the outlook for a ‹criterion›, a common measure, to which everything can be referred, in order to give to that particular branch of knowledge the character of an ‹exact science›. Thus we observe some authors seeking for fixity in ‹value›, others in ‹money›, others in ‹corn›, others in ‹labour›, that is to say, in things which are themselves all liable to fluctuation.