There are no footnotes in this book. A catch-all for the author’s afterthoughts and for the corrections provided by friends who have read manuscript or galley proof—as well as a place for legitimate references—they are often a nuisance and always a typographical eyesore. The reference numbers in this book direct attention only to the sources of quotations, facts, or theories. They do not lead the reader to supplementary text material. Therefore, he may ignore them unless he wants to pursue the subject further for himself, or to verify the authority for what may seem to him an implausible statement.