Published online by Cambridge University Press: 11 May 2016
Keynes abandoned the theoretical approach used in the Treatise on Money, the fundamental equations approach, very soon after publishing the Treatise. One reason why he may have done so is discussed in this paper. Twice in 1931 someone pointed out to Keynes a third fundamental equation, one for the price of investment goods, an equation Keynes had not developed in the Treatise. This third fundamental equation may have shown Keynes that his fundamental equation approach may not be promising or fruitful.