In the following year, 1930, I published The Conquest of Happiness,... This book was differently estimated by readers of three different levels. ... I do not know which estimate was right; what I do know is that the book was written at a time when I needed much self-command and much that I had learned by painful experience if I was to maintain any endurable level of happiness.
Source: The Autobiography of Bertrand Russell, v.2,chap.3: China
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