The Great Depression of 1929 not only shook the foundations of the economy but also those of economics as a science. At that time Keynes was ﬁnishing the Treatise of Money, a work that proposed some changes in the traditional interpretation of the business cycle. While the book was in press, he realized that instead of amending the paradigm he had better shift to a different one. In a letter to George Bernard Shaw, dated 1935, Keynes wrote:
you have to know that I believe myself to be writing a book on economic theory which will largely revolutionize – not, I suppose, at once but in the course of the next ten years – the way the world thinks about economic problems.