"If you are wise you won't be deceived by the innocent airs of those whom you have once found to be dangerous."

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Thus the feeling I sometimes have - which all of us who work closely with aphasiacs have - that one cannot lie to an aphasiac. He cannot grasp your words, and cannot be deceived by them; but what he grasps he grasps with infallible precision, namely the expression that goes with the words, the total, spontaneous, involuntary expressiveness which can never be simulated or faked, as words alone can, too easily.

— Oliver Sacks