#40. The Land Owner's Share--Rent#, the second part of the produce, means, in political economy, what is paid for the use of a natural agent, whether land, or beds of minerals, or rivers, or lakes. The rent of a house or factory is, therefore, not all rent in our meaning of the word. Capital has been spent in building the house or factory, and interest must be paid on this capital; we must then deduct this interest from what is commonly called the rent, before we can find out what is really rent. The ground rent of a house is the rent paid for the ground on which it stands, and this will be more nearly the true rent, apart from interest. Similarly, the ordinary rent of a farm will usually include interest upon the capital spent on the farm buildings, roads, gates, fences, drains, and other improvements. We shall afterwards learn exactly how true rent arises. #41. The Capitalist's Share.# The proper share of the capitalist is #interest#; but this is usually a good deal less than what actually remains in the hands of the capitalist. Business is generally carried on by some capitalist who rents a piece of land, builds a factory, purchases machinery, and then employs men to work the machinery, paying them wages. The capitalist himself often acts as manager, and works every day almost as long as the workmen. When the goods are finished and sold, he keeps the whole of the money he gets for them; but then he has already paid out a large sum as wages, while the goods were being made; another part goes to pay the rent of the land which he has hired. Having struck off these portions, there ought to remain a certain #profit#, part of which he uses to live upon. But even this profit consists of more than interest upon his capital. It should include also a payment for his labour in superintending the business. The manager of a factory may seldom touch the cotton, flax, iron, or other material, which is manufactured; nevertheless, he works with his head and his pen, calculating the prices at which he can produce goods, inquiring where he can buy the materials most cheaply, choosing good workmen, keeping the accounts straight, and so on. Severe mental labour is really far more difficult and exhausting than manual labour; and in raising up a good business, and carrying it through times of danger, a manager has to undergo great anxiety and mental fatigue. Thus, it is necessary that a successful manager should receive a considerable share of the produce, so as to make it worth his while to give this labour. His share is called #the wages of superintendence#, and, although usually much larger than the share of a common labourer, it is really wages of the same nature.