I can date my own personal 'revolution' rather exactly to May or June 1933. It was like this. It began… with Hayek. His "Prices and Production" is one of the influences that can be detected in The Theory of Wages; it could not have been otherwise, for 1931 was a Prices and Production year at the London School of Economics… I did not in fact find it all easy to fit in with my own ideas. What started me off in 1933 was an earlier work of Hayek's, his paper on 'Intertemporal Equilibrium', an idea which I found easier to reduce to my preferred (Paretian or Wicksellian) pattern.
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.
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.