What I am going to tell you about is what we teach our physics students in the third or fourth year of graduate school – and you think I’m going to explain it to you so you can understand it? No, you’re no going to be able to understand it. Why, then, am I going to bother you with all this? Why are you going to sit here all this time, when you won’t be able to understand what I am going to say? It is my task to convince you not to turn away because you don’t understand it. You see, my physics students don’t understand it either. That is because I don’t understand it. Nobody does.
Richard P. Feynman – QED: The Strange Theory of Light and Matter (1985)