she had refused him, had placed an insuperable barrier between her and him.
Leo Tolstoy. Anna Karenina (1878)
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Power, government, war, law, punishment, and a thousand other things, had no terms wherein that language could express them, which made the difficulty almost insuperable, to give my master any conception of what I meant.
Jonathan Swift. Gulliver's Travels Into Several Remote Regions of the World (1726)
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she would not long endure me under the same roof with her; for her glance, now more than ever, when turned on me, expressed an insuperable and rooted aversion.
Charlotte Brontë. Jane Eyre (1847)
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Apart from this insuperable antipathy to her, Princess Mary was agitated just then because on the Rostovs’ being announced,
Leo Tolstoy. War and Peace: With bonus material from Give War and Peace A Chance by Andrew D. Kaufman . Simon & Schuster