On Christmas Eve, 1984, Alberto declared that a “good penultimate draft” of his book would be finished by the end of the year. The day after Christmas he became ill, and in the early morning hours of December 30, he died. The typescript Alberto left behind was, indeed, almost completed: The research had been finished and the arguments and theses were already in place; all but the introduction and the last chapter had been written in full, and extensive notes for those had been drafted. Some portions of the typescript had already been carefully crafted, and the intended shape of much of the rest was clear. In many places Alberto's dry wit showed through – you could almost see behind the prose the tilt of his head, the lopsided smile, the brief twinkle in his eye. With the help of a number of people, that typescript has been readied for publication. Using the notes Alberto left, I have completed the introduction and final chapter. Repetitions, digressions, and minor errors have been removed, theses and arguments delineated more clearly, grammar corrected, prose smoothed – all, I hope, without disturbing the twinkle. The result is not what Alberto would have produced, but perhaps it is something he would have found acceptable. He had intended to write a conclusion, discussing some of the implications of his study for contemporary philosophy. I have not attempted to write that conclusion.