The three-or-four-hours rule for getting creative work done
Charles Darwin, at work on the theory of evolution in his study at Down House, toiled for two 90-minute periods and one one-hour period per day; the mathematical genius Henri Poincaré worked for two hours in the morning and two in the afternoon. Thomas Jefferson, Charles Dickens, Virginia Woolf, Ingmar Bergman and many more all basically followed
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