When we are not busy, our minds tend to become a near-vacuum. [...] Nature also rushes in to fill the vacant mind. With what? Usually with emotions. Why? Because emotions of worry, fear, hate, jealousy, and envy are driven by primeval vigour and the dynamic energy of the jungle. Such emotions are so violent that they tend to drive out of our minds all peaceful, nappy thoughts and emotions.
(November 24, 1888 – November 1, 1955) was an American writer and lecturer and the developer of famous courses in self-improvement, salesmanship, corporate training, public speaking and interpersonal skills. Born in poverty on a farm in Missouri, he was the author of How to Win Friends and Influence People, first published in 1936, a massive bestseller that remains popular today. He also wrote a biography of Abraham Lincoln, entitled Lincoln the Unknown, as well as several other books.