Adam Smith, The Wealth of Nations
Book IV, Chapter III
 To lay extraordinary restraints upon the those particular countries with which the importation of goods of almost all kinds from balance of trade is supposed to be disadvantageous, is the second expedient by which the commercial system proposes to increase the quantity of gold and silver.
 . . . though it were certain that in the case of a free trade between France and England, for example, the balance would be in favour of France, it would by no means follow that such a trade would be disadvantageous to England, or that the general balance of its whole trade would thereby be turned more against it. If the wines of France are better and cheaper than those of Portugal, or its linens than those of Germany, it would be more advantageous for Great Britain to purchase both the wine and the foreign linen which it had occasion for of France than of Portugal and Germany. Though the value of the annual importations from France would thereby be greatly augmented, the value of the whole annual importations would be diminished, in proportion as the French goods of the same quality were cheaper than those of the other two countries. This would be the case, even upon the supposition that the whole French goods imported were to be consumed in Great Britain.
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 Nothing, however, can be more absurd than this whole doctrine of the balance of trade, upon which, not only these restraints, but almost all the other regulations of commerce are founded. When two places trade with one another, this doctrine supposes that, if the balance be even, neither of them either loses or gains; but if it leans in any degree to one side, that one of them loses and the other gains in proportion to its declension from the exact equilibrium. Both suppositions are false. A trade which is forced by means of bounties and monopolies may be and commonly is disadvantageous to the country in whose favour it is meant to be established, as I shall endeavour to show hereafter. But that trade which, without force or constraint, is naturally and regularly carried on between any two places is always advantageous, though not always equally so, to both.
 By advantage or gain, I understand not the increase of the quantity of gold and silver, but that of the exchangeable value of the annual produce of the land and labour of the country, or the increase of the annual revenue of its inhabitants.
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 There is no commercial country in Europe of which the approaching ruin has not frequently been foretold by the pretended doctors of this system from an unfavourable balance of trade. After all the anxiety, however, which they have excited about this, after all the vain attempts of almost all trading nations to turn that balance in their own favour and against their neighbours, it does not appear that any one nation in Europe has been in any respect impoverished by this cause. Every town and country, on the contrary, in proportion as they have opened their ports to all nations, instead of being ruined by this free trade, as the principles of the commercial system would lead us to expect, have been enriched by it. Though there are in Europe, indeed, a few towns which in some respects deserve the name of free ports, there is no country which does so. Holland, perhaps, approaches the nearest to this character of any though still very remote from it; and Holland, it is acknowledged, not only derives its whole wealth, but a great part of its necessary subsistence, from foreign trade.
 There is another balance, indeed, which has already been explained, very different from the balance of trade, and which, according as it happens to be either favourable or unfavourable, necessarily occasions the prosperity or decay of every nation. This is the balance of the annual produce and consumption. If the exchangeable value of the annual produce, it has already been observed, exceeds that of the annual consumption, the capital of the society must annually increase in proportion to this excess. The society in this case lives within its revenue, and what is annually saved out of its revenue is naturally added to its capital, and employed so as to increase still further the annual produce. If the exchangeable value of the annual produce, on the contrary, fail short of the annual consumption, the capital of the society must annually decay in proportion to this deficiency. The expence of the society in this case exceeds its revenue, and necessarily encroaches upon its capital. Its capital, therefore, must necessarily decay, and together with it the exchangeable value of the annual produce of its industry.
 This balance of produce and consumption is entirely different from what is called the balance of trade. It might take place in a nation which had no foreign trade, but which was entirely separated from all the world. It may take place in the whole globe of the earth, of which the wealth, population, and improvement may be either gradually increasing or gradually decaying.
 The balance of produce and consumption may be constantly in favour of a nation, though what is called the balance of trade be generally against it. A nation may import to a greater value than it exports for half a century, perhaps, together; the gold and silver which comes into it during an this time may be all immediately sent out of it; its circulating coin may gradually decay, different sorts of paper money being substituted in its place, and even the debts, too, which it contracts in the principal nations with whom it deals, may be gradually increasing; and yet its real wealth, the exchangeable value of the annual produce of its lands and labour, may, during the same period, have been increasing in a much greater proportion. The state of our North American colonies, and of the trade which they carried on with Great Britain, before the commencement of the present disturbances,*106 may serve as a proof that this is by no means an impossible supposition.