'I have ? read your criticism of my book. I will not say that you have given no twinges to my vanity; but I will say that I am in perfect charity with my critic. I should have preferred it if you had been a convert & admitted that every word I said was true. But I am quite satisfied to have a candid & generous critic & that you could not cease to be without ceasing to be yourself. Most of the points between us would require a treatise instead of a letter. As, for example, I can never understand what is meant to aversion & desire [to] expect anticipation of pain & pleasure. Therefore to me it is the same thing to say that conduct is determined by one or the other. But this implies a psychological difference not to be bridged over in a letter.'