Published in 1909, this book explores the causes and consequences of mental fatigue. The author, Tsuru Arai, was a Japanese physician and psychologist who is best known for his work on occupational health. In this book, he discusses the role of mental strain in causing fatigue, and offers suggestions for preventing and treating it. He also examines the impact of fatigue on productivity and well-being, both for individuals and for society as a whole.

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