Parenthood had made it imperative to earn money. ...In 1922 I published a book on China, and in 1923 (with my wife Dora) a book on The Prospects of Industrial Civilization, but neither of these brought much money. I did better with two small books, The A.B.C. of Atoms (1923) and The ABC of Relativity (1925), and with two other small books, Icarus or The Future of Science (1924) and What I Believe (1925 ) . In 1924 I earned a good deal by a lecture tour in America. But I remained rather poor until the book on education in 1926. After that, until 1933, I prospered financially, especially with Marriage and Morals (1929) and The Conquest of Happiness (1930) . Most of my work during these years was popular, and was done in order to make money, but I did also some more technical work.
Source: The Autobiography of Bertrand Russell, v.2
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