E D I T O R I A L M E T H O D x c i x In the case of published items, we take the first version published in the original language as our primary text. Variations in later editions of Einstein’s publications that were prepared during his lifetime are noted. If an original manuscript is avail- able, small differences are recorded in endnotes. If the manuscript diverges sub- stantially from the printed version, the dissimilar portions of the manuscript are presented as a separate text, preceding the printed version. When no manuscript, typescript, or printed version in the original language is available, a published translation is used. If in addition to a German original text, a translation into a dif- ferent language was authorized by Einstein as the first or only published version, both versions of the text are printed. Where a set of discussion fragments in Einstein’s hand exists, these will serve as the source of a text, rather than the published version of those remarks. Significant variations in all available texts will be noted. PRESENTATION With some exceptions noted below, all texts are presented chronologically. Writ- ings precede letters of the same date. In the case of undated documents to which a date range has been attributed by the editors, the earliest date determines their position in the volume. An undated text enclosed with, or inserted in, a document follows the latter, unless evidence suggests a different placement. When a document is enclosed with a letter that serves only as a cover letter, with no independent character of its own, the two items are presented together. Documents that have come to the attention of the editors after the publication of the volume in which they would have appeared chronologically are presented at the front of a subsequent volume. Within a given volume, each document is given a sequential number. Transcriptions of text fragments from dealer or auction catalogs are presented when the original or a copy of the original is not available. Repetitious text fragments and unrelated text or equations appearing in a draft are omitted, but their existence is mentioned in the descriptive note. All published articles or books are presented in facsimile. If a facsimile is illeg- ible, the text will be presented in transcription. For the improvement of legibility, some facsimiles will be digitally enhanced by the editors. Original drawings are rendered as scanned or redrawn images.