If we desire to make a definite statement of the amount of economic well-being which a man possesses we may say that he is worth a hundred thousand dollars. Or we may state the same thing in another way by saying that he has an income of five thousand dollars a year. In the one case we state the amount of wealth he has at a given instant of time; in the other case we state the amount of income which his wealth brings him during a given period of time. We speak of both wealth and income in terms of money, but the real wealth and the real income consist not of money but of the things which may be used to gratify wants. In another sense we may consider income as a flow of gratifications of our wants which comes from the possession of wealth. Thus if we own the house in which we live, the house is our wealth but it is not our income. The flow of utilities that comes to us from the possession of the house is income. Income, in this sense, is a flow of gratifications of wants. In the chapter on Interest we shall discuss the relation between the valuation of the income and the valuation of the wealth from which it flows.