7. The case which we have just examined, is an example in how remarkable a manner every cause which materially influences exports, operates upon the prices of imports. According to the ancient theory of the balance of trade, and to the associations of the generality of what are termed practical men to this day, the sole benefit derived from commerce consists in the exports, and imports are rather an evil than otherwise. Political economists, seeing the folly of these views, and clearly perceiving that the advantage of commerce consists and must consist solely of the imports, have occasionally suffered themselves to employ language evincing inattention to the fact, that exports, though unimportant in themselves, are important by their influence on imports. So real and extensive is this influence, that every new market which is opened for any of our goods, and every increase in the demand for our commodities in foreign countries, enables us to supply ourselves with foreign commodities at a smaller cost. Let us revert to our earliest and simplest example, but which displays the real law of interchange more luminously than any formula into which money enters; the case of simple barter. We showed, that if at the rate of 10 yards of cloth for 17 of linen, the demand of Germany amounted to 1000 times 10 yards of cloth, the two nations will trade together at that rate of interchange, provided that the linen required in England be exactly 1000 times 17 yards, neither more nor less. For the cloth and the linen will then exactly pay for one another, and nobody on either side will be obliged to offer what he has to sell at a lower rate, in order to procure what he wants to buy. Now if the increase of wealth and population in Germany should greatly increase the demand in that country for cloth, the demand for linen in England not increasing in the same ratio,--if, for instance, Germany became willing, at the above rate, to take 1500 times 10 yards; is it not evident, that to induce England to take in exchange for this the only article which Germany by supposition has to give, the latter must offer it at a rate more advantageous to England--at 18, or perhaps 19 yards, for 10 of cloth? So that the division of the advantage becomes more and more favourable to a country, in proportion as the demand for its commodities increases in foreign countries.