In a period spanning nearly half a century, from 1888 to 1935, Heinrich Schenker wrote to and received letters, postcards, calling cards, telegrams, etc. from about 400 correspondents—journal editors, publishers, professional musicians, librarians, archivists, Viennese officials and institutions, societies, members of the Brahms circle, patrons, composers, visual artists, music critics, authors, scholars, pupils, followers, family members, and personal friends.
This correspondence is now widely dispersed in Europe and the USA. Much of it is preserved in two dedicated Schenker archives (Riverside, California; New York), in public libraries and archives (Vienna, Berlin, Marburg, etc.), in the archives of commercial companies and private institutions, and in private family possession. Some 7,500 documents are known to survive.
In fact, Schenker corresponded with many more people and organizations than the 400 represented in the surviving materials. There are many “ghost” correspondences, i.e. written exchanges that no longer survive but which are noted in the diaries and whose content can be at least partly reconstructed with the aid of summaries recorded in the diaries. In addition, SDO regularly tracks down hitherto unidentified caches of correspondence and brings them to publication.
Correspondences range from a single item to over a thousand. The most extensive are those with Universal Edition and its representatives (1,260 items), Moriz, Valerie, and Fanny Violin (1,026), Drei Masken Verlag and its representatives (384), J. G. Cotta (293), Reinhard Oppel (225), and Hans Weisse (214). They include renowned people from many walks of life: the composers Paul Hindemith, Ferruccio Busoni, and Arnold Schoenberg, the musicians Wilhelm Furtwängler, Johannes Messchaert, Moriz Rosenthal, and Paul Wittgenstein, the musicologists Guido Adler, Otto Erich Deutsch, Alfred Einstein, and Anthony van Hoboken, the critics and editors Eduard Hanslick and Maximilian Harden, and the military leaders Erich Ludendorff and Paul von Hindenburg.
These encompass everything from the most formalized official missives to the most personal intimations: a vast spectrum of communications reflecting everything from technical music theory, through aesthetics, through political and economic affairs, to details of family and domestic life. They represent every conceivable type of relationship between two correspondents, and as such afford deep insight in Schenker's personal psychology, life, and work.