THE WEALTH OF NATIONS.

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gradation of the value of silver, but of the rise in their realprice.

Different Effects of the Progress of Improvement uponthree different Sorts of rude Produce.

These different sorts of rude produce may be divided intothree classes. The first comprehends those which it is scarcein the power of human industry to multiply at all. The se-cond, those which it can multiply in proportion to the de-mand. The third, those in which the efficacy of industry iseither limited or uncertain. In the progress of wealth andimprovement, the real price of the first may rise to any degreeof extravagance, and seems not to be limited by any certainboundary. That of the second, though it may rise greatly,has, however, a certain boundary beyond which it cannot wellpass for any considerable time together. That of the third,though its natural tendency is to rise in the progress of im-provement, yet in the same degree of improvement it maysometimes happen even to fall, sometimes to continue thesame, and sometimes to rise more or less, according as dif-ferent accidents render the efforts of human industry, in mul-tiplying this sort of rude produce, more or less successful.

First Sort.

The first sort of rude produce of which the price rises inthe progress of improvement, is that which it is scarce in thepower of human industry to multiply at all. It consists inthose things which nature produces only in certain quantities,and which being of a very perishable nature, it is impossibleto accumulate together the produce of many different seasons.Such are the greater part of rare and singular birds and fishes,many different sorts of game, almost all wild-fowl, all birdsof passage in particular, as well as many other things. Whenwealth and the luxury which accompanies it increase, the de-mand for these is likely to increase with them, and no effortof human industry may be able to increase the supply muchbeyond what it was before this increase of the demand. Thequantity of such commodities, therefore, remaining the same,or nearly the same, while the competition to purchase themis continually increasing, their price may rise to any degreeof extravagance, and seems not to be limited by any certainboundary. If woodcocks should become so fashionable as tosell for twenty guineas a-piece, no effort of human industrycould increase the number of those brought to market, much