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The Collected Works of Karen Horney‎ (1957) by Karen Horney, p. 154: "We may feel genuinely concerned about world conditions, though such a concern should drive us into action and not into a depression."

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Terence, in Heauton Timoroumenos [The Self-Tormentor]

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Quoted in Grist: The National Conference on State Parks magazine, 1965 [https://books.google.fr/books?id=u8VH4AZ1va4C&newbks=1&newbks_redir=0&dq=The%20oldest%2C%20shortest%20words%E2%80%94%20%22yes%22%20and%20%22no%22%E2%80%94%20are%20those%20which%20requ

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This is often published as a direct quote of Pythagoras, but seems to be derived from the account of Diogenes Laertius of Pythagorean doctrines, where he simply describes the statement as a precept of his followers. In the translation of C. D. Yonge (1853