There is one necessary augmentation upon the prices of industry, brought about by a very natural cause, viz. the increase of population, which may imply a more expensive improvement of the soil; that is, an extension of agriculture. This augmentation may very probably put a stop to the augmentation of demand for many branches of manufactures, consequently may stop the progress of industry; and if the same causes continue to operate in a greater degree, it may also cut off a part of the former demand, may discredit the market, open a door to foreign consumption, and produce the inconveniencies of poverty and distress, in proportion to the degree of negligence in the statesman. I shall now give another example, of a very natural augmentation upon the intrinsic value of work, which does not proceed from the increase of population, but from the progress of industry itself; which implies no internal vice in a state, but which is the necessary consequence of the reformation of a very great one. This augmentation must be felt less or more in every country, in proportion as industry becomes extended. We have said, that the introduction of manufactures naturally tends to purge the lands of superfluous mouths: now this is a very slow and gradual operation. A consequence of it was said to be (Book I. Chap. xx.) an augmentation of the price of labour, because those who have been purged off, must begin to gain their whole subsistence at the expence of those who employ them. If therefore, in the infancy of industry, any branch of it shall find itself assisted in a particular province, by the cheap labour of those mouths superfluously fed by the land, examples of which are very frequent, this advantage must diminish, in proportion as the cause of it ceases; that is, in proportion as industry is extended, and as the superfluous mouths are of consequence purged off.