Labour and capitals tend naturally to diffuse themselves through every species of employment; and, as certain employments are, by their nature, accompanied with inconveniencies and difficulties which do not occur in others, while these, on the contrary, offer some real or imaginary advantages which are peculiar to themselves; wages and profits should rise and fall in proportion to these advantages and disadvantages; thus forming a complete equilibrium between the various kinds of employment. The arbitrary and oppressive policy of Europe, in many instances, opposes the establishment of this equilibrium, which is conformable to the order of nature--book 1, chap. x. Of the _rent_ of the ground. The nature of rent: the manner in which it enters into the price of wealth; and according to what principles it in some cases forms an integral part of that price, while in others it does not--book 1, chap. xi. Division of the rude produce of the earth into two great classes: 1. That produce which is always necessarily disposed of in such a way as to bring a rent to the landed proprietor. 2. That which, according to circumstances, may be disposed of so as to bring, or so as not to bring, a rent. The produce of the first description is derived from the ground appropriated to furnishing subsistence for man, or for those animals which he uses as food. The value of the produce of the ground cultivated for the support of man, determines the value of the produce of all other ground proper for this species of culture. This general rule allows of some exceptions. Causes of these exceptions. The produce of the second class consists of the materials of clothing, lodging, fuel, and the ornaments of dress and furniture. The value of this species of produce depends on that of the first description. Some circumstances render it possible that the produce of the second kind may be disposed of in such a way as to furnish a rent to the landed proprietor. Principles which regulate the proportion of the price of these products, which is formed by the rent--book 1, chap. xi. Relation between the respective values of the produce of the first class, and those of the produce of the second. Variations which may take place in this relation, and the causes of such variations--ibid. Relation existing between the values of the two descriptions of rude produce above mentioned, and the values of the produce of manufacture. Variations which may occur in this relation--ibid. Certain kinds of rude produce, procured from very different sources, are, however, intended for the same kind of consumption; and hence it happens, the value of one determines and limits that of another--ibid. The relations between values of different natures vary according to the state of society. This state is _improving_, _declining_, or _stationary_; that is to say, society is either increasing in wealth, or falling into poverty, or remaining in the same unchanged state of opulence.