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Rh consider the fertility of its soil but also its accessibility, or, in other words, its convenience of situation. Some of the most fertile land in the world is so remote from any population which requires its produce, that its cultivation would prove unremunerative, and therefore it may be regarded as unproductive of wealth. Confusion frequently arises because a productive soil and a fertile soil are regarded as synonymous expressions. In an economic treatise, however, it must be always carefully remembered that not only fertility but also convenience of situation are included when the term 'productive' is applied to land.

Bearing these remarks in mind, it is evident that the productiveness of land varies inversely with the quantity of labour and capital required not only to raise a certain amount of produce, but also to bring the produce to the situation where it is required. The most fertile land, if extremely remote from the population which is willing to purchase its produce, is frequently unproductive, because of the great expense which cost of carriage would involve. As population increases, unless the additional food required can be obtained either by foreign importation or by improved agriculture, the area of cultivation is extended, and less productive soils must be resorted to; or, in other words, land is gradually brought into cultivation which does not return so much for the labour and capital expended upon it, as land which was previously cultivated. Hence the production of wealth cannot be indefinitely increased, because the returns to labour and capital diminish, as it becomes necessary to resort to less productive land. This principle forms the basis of Ricardo's theory of Rent, or as it is sometimes called, the theory of diminishing productiveness.

The proposition just enunciated suggests an obstacle which more or less impedes the continual increase in the production of wealth. The reader, for several reasons, finds it difficult adequately to appreciate the magnitude of the impediment which in many countries is thus placed upon the production of wealth. It will be necessary frequently to recur to this subject; a few more remarks may, however, be here made upon it with advantage. It may be thought that although less