To believe in something not yet proved and to underwrite it with our lives: it is the only way we can leave the future open. Man, surrounded by facts, permitting himself no surmise, no intuitive flash, no great hypothesis, no risk, is in a locked cell. Ignorance cannot seal the mind and imagination more surely.

Learning

When you stop learning, stop listening, stop looking and asking questions, always new questions, then it is time to die.