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. FeynmanIf science is to progress, what we need is the ability to experiment, honesty in reporting resultsโthe results must be reported without somebody saying what they would like the results to have beenโand finallyโan important thingโthe intelligence to interpret the results.
Richard P. FeynmanMy friends and I had taken dancing lessons, although none of us would ever admit it. In those depression days, a friend of my mother was trying to make a living by teaching dancing in the evening, in an upstairs dance studio. There was a back door to the place, and she arranged it so the young men could come up through the back way without being seen.
Richard P. FeynmanI have the advantage of having found out how hard it is to get to really know something. How careful you have to be about checking your experiments. How easy it is to make mistakes and fool yourself. I know what it means to know something.
Richard P. Feynman