For want of this just balance, no trading state has ever been of long duration, after arriving at a certain height of prosperity. We perceive in history the rise, progress, grandeur, and decline of Sydon, Tyre, Carthage, Alexandria, and Venice, not to come nearer home. While these states were on the growing hand, they were powerful; when once they came to their height, they immediately found themselves labouring under their own greatness. The reason of this appears from what has been said. While there is a demand for the trade of any country, inhabitants are always on the increasing hand. This is evident from what has been so often repeated in the first book, and confirmed by thousands of examples. There never was any branch of trade established in any kingdom, province, city, or even village; but such kingdom, province, &c. increased in inhabitants. While this gradual increase of people is in proportion to the growing demand for hands, the balance between work and demand is exactly kept up: but as all augmentations must at last come to a stop, when this happens, inconveniencies must ensue, greater or less, according to the negligence of the statesman, and the violence or suddenness of the revolution. ------------------------------------------------------------------------ CHAP. XI. _Why in Time this Balance is destroyed._ Now let us examine what may be the reason why, in a trading and industrious nation, time necessarily destroys the perfect balance between work and demand. We have already pointed out one general cause, to wit, the natural stop which must at last be put to augmentations of every kind. Let us now apply this to circumstances, in order to discover in what manner natural causes operate this stop, either by preventing the increase of work, on one side of the balance, or the increase of demand, on the other. When once we discover how the stop is put to augmentations, we may safely conclude, that the continuation of the same, or similar causes, will soon produce a diminution, and operate a decline. We have traced the progress of industry, and shewn how it goes hand in hand with the augmentation of subsistence, which is the principal allurement to labour. Now the augmentation of food is relative to the soil, and as long as this can be brought to produce, at an expence proportioned to the value of the returns, agriculture, without any doubt, will go forward in every country of industry. But so soon as the progress of agriculture demands an additional expence, which the natural return, at the stated prices of subsistence, will not defray, agriculture comes to a stop, and so would numbers, did not the consequences of industry push them forward, in spite of small difficulties. The industrious then, I say, continue to multiply, and the consequence is, that food becomes scarce, and that the inhabitants enter into competition for it.