We cannot define anything precisely. If we attempt to, we get into the paralysis of thought that comes to philosophers, who sit opposite each other, one saying to the other, "You don't know what you are talking about!" The second one says, "What do you mean by know? What do you mean by talking? What do you mean by you?"
Richard P. FeynmanThe "paradox" is only a conflict between reality and your feeling of what reality "ought to be."
Richard P. FeynmanIf I say [electrons] behave like particles I give the wrong impression; also if I say they behave like waves. They behave in their own inimitable way, which technically could be called a quantum mechanical way. They behave in a way that is like nothing that you have seen before.
Richard P. FeynmanThere is no learning without having to pose a question. And a question requires doubt.
Richard P. FeynmanI find that teaching and the students keep life going, and I would never accept any position in which somebody has invented a happy situation for me where I don't have to teach. Never.
Richard P. Feynman