Do not grow old, no matter how long you live. Never cease to stand like curious children before the Great Mystery into which we were born.

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Everyone knew it was impossible, until a fool who didn't know came along and did it.

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Failure is success in progress

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Wisdom is not a product of schooling but of the lifelong attempt to acquire it.

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Condemnation before investigation is the highest form of ignorance.

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Strive not to be a success, but rather to be of value.

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Three great forces rule the world: stupidity, fear and greed.

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I believe we are here to do good. It is the responsibility of every human being to aspire to do something worthwhile, to make the world a better place than the one we found.

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Thinking is hard work; that's why so few do it.

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What you can't imagine, you can't discover.

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