It remains now to consider certain important consequences which flow from this explanation of rent. In the first place, it is evident that three separate incomes are derived from agriculture, whilst two only make their appearance in all other industries. In common with them agriculture furnishes reward or income for two classes of persons--wages for labourers and profit for the employer. There the similarity ends. A third income makes its appearance for a third person--rent for the landlord. This rent is not an ordinary consideration for hiring some useful machine; if it were a compensation of this nature, it would necessarily take its place amongst the items composing the cost of production. It is a part of the profit won, dependent in no way on the value of the property nor on the price at which it was bought, but purely and simply on the degree of the profit realized. It is a part of that profit, estimated and paid as what remains over--a surplus. But how comes it to pass that an ordinary manufacture does not yield or pay any such third income? For a simple and decisive reason. A Manchester manufacturer cannot permanently earn a higher profit than belongs to his trade. If we suppose 10 per cent. to be the natural profit of that trade, and he persistently realizes 18, other mills will be opened by new men entering into the business, and this process will be continued till his profits are reduced to their legitimate level. It is otherwise with farming. If a tenant reaps 10 per cent. continuously from his farm, when competitors are willing to be content with 8, the landlord will quickly make the discovery, and will add the surplus 2 to the rent he requires. He will obtain the income, because 8 per cent. is judged by the farming world to be an adequate reward for engaging in agriculture, and because no additional land is to be found for the agricultural business.