NOTE ON SYMBOLS
I have found it convenient, especially in Appendix A, to use the symbol <, following a date, to indicate an uncertain date not earlier than that named, and the symbol >, followed by a date, to indicate an uncertain date not later than that named. Thus 1903 <> 23 would indicate the composition date of any part of this book. I have sometimes placed the date of a play in italics, where it was desirable to indicate the date of production rather than publication.
