x c E D I T O R I A L M E T H O D Signatures are placed flush right. Postscripts are placed flush left on the line be- neath the signature. Editorial endnotes, indicated by raised Arabic numerals enclosed in square brackets, follow the descriptive note. The Calendar of Abstracts includes, in chronological order, letters that are not presented as full texts. The entries summarize the contents of each document. (See the introductory paragraph in the Calendar of Abstracts for a more detailed descrip- tion.) TRANSCRIPTION We aim in our transcriptions to maintain substantial faithfulness to the original texts. No corrections, additions, deletions, or changes of characters, punctuation, or arrangement are made except as set forth below. Non-Latin scripts are transcribed into Latin type, with the exception of Cyrillic. Indentation is used when an author used a vertical line to indicate a new para- graph when the paragraphing is ambiguous but a paragraph was probably intend- ed and if the author’s style is to start a new paragraph by placing the first line flush with the left margin. A closure in a letter is printed as one continuous text, and commas are silently provided where appropriate. Unusual or confusing abbreviations are expanded within square brackets. When the text of letters is obscured or difficult to read, a probable reading is placed within square brackets, with an assumption of correct spelling, grammar, and syntax. When no such reading is possible, three dashes within square brackets are inserted for each illegible word. When the author uses square brackets, it is so noted. Authors’ deletions that are deemed insignificant are omitted without comment. Those deemed significant are placed within angle brackets preceding the revised text. The text of a deletion within a deletion is struck within the angle brackets. If a portion of a text greater than one line has been deleted as a whole, the deletion will be noted by a diagonal line running from the upper left to the lower right. When the author cancels part of an equation for calculational purposes, this is noted with a diagonal line running from the lower left to the upper right. In mathematical research notes and calculations, deletions and cancellations may also be shown graphically in a way that imitates the original. Superscript and subscript interlineations are brought down to the line interlin- eations are noted when significant.