“We cannot define anything precisely! If we attempt to, we get into that 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?,’ and so on. In order to be able to talk constructively, we just have to agree that we are talking about roughly the same thing.” – Richard P. Feynman, The Feynman Lectures on Physics, Vol. I (emphases in original)