"I was once in a situation where I was giving a lecture, and I had some equations on the board. A guy in the audience stood up and said, 'Professor Feynman, your equations are wrong!' I looked at them …"

"I have a great deal of difficulty with the idea of 'truth' in the philosophical sense."

"If you thought that science was certain — well, that is just an error on your part."

"The price of doing science is the necessity of not being a know-it-all."

"You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird. You'll only know about humans in different places a…"