Dirac & Canonical Quantization
(Courtesy of Monica Dirac) "I went back to Cambridge at the beginning of October 1925, and resumed my previous style of life, intense thinking about these problems during the week and relaxing on Sunday, going for a long walk in the country alone. The main purpose of these long walks was to have a rest so that I would start refreshed on the following Monday. It was during one of the Sunday walks in October 1925, when I was thinking about this (uv − vu), in spite of my intention to relax, that I thought about Poisson brackets. I remembered something which I had read up previously, and from what I could remember, there seemed to be a close similarity between a Poisson bracket of two quantities and the commutator. The idea came in a flash, I suppose, and provided of course some excitement, and then came the reaction "No, this is probably wrong". I did not remember very well the precise formula for a Poisson bracket, and only had some vague recollections. But there were ex...