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That's where all the trouble in life comes from. Thinking.

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Sometimes what you think is an end is only a beginning. And that wouldn't do at all.

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A meal should always lie lightly on the estomac," said Poirot. "It should not be so heavy as to paralyze thought.

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Poirot," I said. "I have been thinking.""An admirable exercise my friend. Continue it.

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Nobody knows what another person is thinking. They may imagine they do, but they are nearly always wrong.

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What I think is a different matter. Maybe I think some rather curious things—but until thinking's got you somewhere it's no use talking about it.