“Did you think the lion was sleeping because he didn't roar?”
Die Verschwörung des Fiesco (The Conspiracy of Fiesco), Act I, sc. xviii (1783)
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Friedrich Schiller 111
German poet, philosopher, historian, and playwright 1759–1805Related quotes
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Bombastes Furioso (1810), Act i, scene 4, reported in Bartlett's Familiar Quotations, 10th ed. (1919).

“Americans used to roar like lions for liberty; now we bleat like sheep for security.”

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Source: Small Great Things

“So great was the extremity of his pain and anguish that he did not only sigh but roar.”
Job 3.
Commentaries

"Ali in Battle" an account of Ali ibn Abi Talib's explanation as to why he declined to kill someone who had spit in his face as Ali was defeating him in battle, in Ch. 20 : In Baghdad dreaming of Cairo
Disputed, The Essential Rumi (1995)