The General Theory of Employment, Interest and Money
The first book of "The General Theory of Employment, Interest and Money" is a repudiation of Say's Law. The classical view for which Keynes made Say a mouthpiece held that the value of wages was equal to the value of the goods produced, and that the wages were inevitably put back into the economy sustaining demand at the level of current production. Hence, starting from full employment, there cannot be a glut of industrial output leading to a loss of jobs. As Keynes put it on p. 18, "supply creates its own demand".