Independently of the variations in the value of money, which necessarily affect wages, but which we have here supposed to have no operation, as we have considered money to be uniformly of the same value, wages are subject to a rise or fall from two causes: 1st. The supply and demand of labourers. 2dly. The price of the commodities on which the wages of labour are expended. In different stages of society, the accumulation of capital, or of the means of employing labour, is more or less rapid, and must in all cases depend on the productive powers of labour. The productive powers of labour are generally greatest when there is an abundance of fertile land: at such periods accumulation is often so rapid, that labourers cannot be supplied with the same rapidity as capital. It has been calculated, that under favourable circumstances population may be doubled in twenty-five years; but under the same favourable circumstances, the whole capital of a country might possibly be doubled in a shorter period. In that case, wages during the whole period would have a tendency to rise, because the demand for labour would increase still faster than the supply. In new settlements, where the arts and knowledge of countries far advanced in refinement are introduced, it is probable that capital has a tendency to increase faster than mankind: and if the deficiency of labourers were not supplied by more populous countries, this tendency would very much raise the price of labour. In proportion as these countries become populous, and land of a worse quality is taken into cultivation, the tendency to an increase of capital diminishes; for the surplus produce remaining, after satisfying the wants of the existing population, must necessarily be in proportion to the facility of production, viz. to the smaller number of persons employed in production. Although, then, it is probable, that under the most favourable circumstances, the power of production is still greater than that of population, it will not long continue so; for the land being limited in quantity, and differing in quality; with every increased portion of capital employed on it, there will be a decreased rate of production, whilst the power of population continues always the same.