"I had the feeling that the stuff was beautiful. I learned it from Weyl, and Weyl had the art of putting things in a lovely perspective. More so than anybody else I have ever read. That book was just a treat. So the feeling of ‘rotten’ would be the absolutely last feeling I would ever have about it. ‘Beautiful’ is what I would call it. To me it’s the magic way to do it. I think that having started early and having used it in lots of different contexts, all the way from my doctor’s thesis on the dispersion and absorption of light in a helium atom, to nuclear physics, to the decay of elementary particles, I feel absolutely at home with it. But John Bell’s question I certainly sympathize with. An ‘irreversible act of amplification’? As Eugene Wigner always says, ‘What means it "irreversible"?’ [...] I think it is just wonderful to have puzzles like that staring us in the face. You’d be amused. Every day I try to write down something in my notebook, although I don’t always succeed, pushing things ahead just a little bit. I only got in two or three sentences this morning. ‘Nada. The photon doesn’t exist in the atom. It doesn’t exist in the photodetector after the act of emission, and you have no right to talk of what it’s doing in between. Nada—it’s nothing.’ Then there’s the irreversible act of amplification where you’ve got a whole lot of things. It’s nada to nada."