The changes which constitute or contribute to material progress are three: increase in population, improvement in the arts of production and exchange, and improvement in knowledge, government, and morals. The effect of increase of population upon the distribution of wealth is to increase rent, and consequently to diminish the proportion of the produce which goes to capital and labour in two ways. First, by lowering the margin of cultivation; and second, and more important, by bringing out in land special capabilities otherwise latent, and by attaching special capabilities to particular land. The effect of inventions and improvements in the productive arts, including division of labour between individuals, is to save labour--that is, to enable the same result to be secured with less labour, or a greater result with the same labour, and hence to the production of wealth. Without any increase in population, the progress of invention constantly tends to give a larger and larger proportion of the produce to the owners of land, and a smaller proportion to labour and capital; and, therefore, to decrease wages and interest. And, as we can assign no limit to the progress of invention, neither can we assign any limits to the increase of rent short of the whole produce. Another cause of the influence of material progress upon the distribution of wealth is the confident expectation of the future enhancement of land values which arises in all progressive countries from the steady increase of rent. This leads to speculation, or the holding of land for a higher price than it would otherwise bring. It is a force which constantly tends to increase rent in a greater ratio than progress increases production, and tends to reduce wages, not merely relatively but absolutely. _III.--The Common Right to Land_ The fact that the speculative advance in land values cuts down the earnings of labour and capital, and checks production, leads irresistibly to the conclusion that this is the main cause of those periodical industrial depressions to which every civilised country seems increasingly liable.