At any rate, this book made him famous, and it enabled him to begin a career as a journalist and author. After the war, Keynes combined teaching a private seminar at Cambridge with his official life in London, where he sat on several government commissions and supervisory boards. He was a busy and much respected public figure. He speculated on the Stock Exchange, on his own account and for other people, with varying success. His first really theoretical work in economics came out only in 1930, in two volumes, written under the influence of the Great Depression: A Treatise on Money. 

His most famous work, The General Theory of Employment, Interest and Money followed six years later. The book is non-technical. Paul Samuelson, one of the American scholars who spent a lot of time translating Keynes's ideas into the language of traditional neoclassical economics, bringing about what he called the "neoclassical synthesis", found it exasperating and inspiring at the same time: 

It is a badly written book, poorly organized . . . it is arrogant, bad-tempered, polemical . . . it abounds in mare's nests and confusions: involuntary unemployment, wage units, the equality of savings and investments, the timing of the multiplier, interactions of marginal efficiency upon the rate of interest and many others . . . flashes of insight and intuition intersperse tedious algebra. An awkward definition suddenly gives way to an unforgettable cadenza. When it is finally mastered, we find its analysis to be obvious and at the same time new. In short, it is a work of genius.

Meanwhile, Friedrich Hayek had joined the London School of Economics in 1931. The two men saw quite a lot of each other, and even though they disagreed on economics as much as on lifestyles, they became friends. Keynes was cool, Hayek was stern. Keynes liked to be a provocative and sometimes brutal nonconformist, while Hayek was polite in a very old-fashioned way and deeply respected tradition, including religion, as the condensed form of human experience passed on from generation to generation. But they were both erudite people who enjoyed each other's conversation, and they were both bibliophiles. When the LSE was evacuated to Cambridge during the Blitz, Keynes helped Hayek find accommodation there. 

In the intellectual dispute between Hayek and Keynes, their two very different temperaments came out very clearly at the beginning of the Thirties. Hayek wrote a scrupulous and precise review of Keynes's Treatise on Money, criticising the lack of a well-argued capital theory, and providing Keynes with some insights into the Austrian theory of capital that he might want to consider in his work. When Keynes finally responded, he just shrugged and said that he no longer believed what he had written in that book.