"It is usually a good idea to bear in mind the distinction between philosophy and an empirical science such as psychology. I once received a valuable lesson in this. A very distinguished astronomer visited the Department of Philosophy in Princeton and gave us a lecture entitled “An Astronomer’s Philosophy.” We philosophers were delighted. And I in my enthusiasm offered to reciprocate by giving a lecture to the astronomers which was to be entitled “A Philosopher’s Astronomy.” But this proposal was received by the astronomers with marked coldness."