"My stay was nearly over when one day Ed Witten said to me, "I just learnt a new way to find exact S-matrices in two dimensions invented by Zamolodchikov and I want to extend the ideas to supersymmetric models. You are the S-matrix expert, aren't you? Why don't we work together?" I was delighted. All my years of training in Berkeley gave me a tremendous advantage over Ed—for an entire week."