In this book we are attempting to o'er a modi'cation of Dirac's theory of the electron we believe to be free of the usual paradoxa, so as perhaps to be acceptable as a clean quantum-mechanical treatment. While it seems to be a fact that the classical mechanics, from Newton to E- stein's theory of gravitation, o'ers a very rigorous concept, free of contradictions and able to accurately predict motion of a mass point, quantum mechanics, even in its...