There are none so blind as those, that will not see

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It is impossible make someone pay attention to something if they are too stubborn

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John Heywood, ‘Random House Dictionary of Popular Proverbs and Sayings’ 1546 and similar to Jeremiah 5:21: ‘Hear now this, O foolish people, and without understanding; which have eyes, and see not; which have ears, and hear not’