Income No. 3 must be defined as the maximum amount of money which the individual can spend this week, and still be able to spend the same amount in real terms in each ensuing week. Value and capital (1939)
The purpose of income calculations in practical affairs is to give people an indication of the amount which they can consume without impoverishing themselves. Following out this idea, it would seem that we ought to define a man's income as the maximum value which he can consume during a week, and still expect to be as well off at the end of the week as he was at the beginning. Value and capital (1939)
The standard stream corresponding to Income No. 3 is constant in real terms... We ask... how much he would be receiving if he were getting a standard stream of the same present value as his actual expected receipts. This amount is his income. Value and capital (1939)