As to diseases, make a habit of two things: to help, or at least to do no harm.

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  Life is short, art long, opportunity fleeting, experiment treacherous, judgment difficult.

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  Facts do not cease to exist because they are ignored.

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  The greatest amount of knowledge, if it has not been worked over by one’s own thinking, is worth much less than a far smaller amount that has been thoroughly thought through.

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  A man of genius makes no mistakes. His errors are volitional and are the portals of discovery.

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  Happy is he who has been able to learn the causes of things.

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  Extraordinary claims require extraordinary evidence.

All quotes