The role of the pion, though it was double because it was also in the limit of the conservation of axial vector charge, it was also the zero mass boson associated with its conservation in that limit. How did we put that in? Was the… should we regard the axial charges after all as producing degeneracy instead of producing zero mass bosons? All of these things were troublesome. Another thing was the parallel between the leptons and the hadrons. If the fundamental group for the hadrons was SU(3)… for classifying the hadrons and for the strong interaction was SU(3);  that suggested  a  parallel with the three leptons: electron, muon and neutrino. But what about the red and blue neutrinos? If there really were red and blue neutrinos, and the experiment hadn't been done yet, then there would be four. Does that mean there ought to be an SU(4) for the hadrons? In other words, should we have charm? But I didn't of course use that word or that idea, but that was the basic question, and I was uncertain about that.

Another thing was the weak interaction: should the weak… if the parallel was with three leptons, then we might think that the weak interaction would be half strangeness preserving and half strangeness changing; like e plus mu over the square root of two times neutrino, if there were one neutrino. But if there were two neutrinos, then we would rather have what Lévy and I had proposed from Paris: namely an angle between the neutron and the lambda: n cosine theta plus lambda sine theta–what was later called the Cabibbo angle. But we actually suggested it because although we wrote cosine theta as one over the square root of one plus epsilon squared, and we wrote sine theta as epsilon over the square root of one plus epsilon squared. But of course that's exactly the same thing–for every theta there's an epsilon, for every epsilon there's a theta; it's exactly the same formula. So I didn't know whether to propose that the strangeness changing weak interaction would be just a little extra bit of the weak interaction, or whether it would be on an equal footing with the strangeness preserving part. I liked the idea of the epsilon, because it made the coupling constants come out perfect, absolutely perfect as Lévy and I had remarked in our paper from Paris the previous year. On the other hand the parallel with electron and muon with one neutrino would suggest that the strangeness changing and strangeness preserving parts would be on a par. I didn't know where to have it.

All of these hesitations and worries I described in that paper that I wrote in 1983 for the Catalonia meeting. It was published several years later, when the proceedings of that conference came out;  the first troubadour they called it, the first troubadour in the history of science.