The name of Felix Mendelssohn Bartholdy (1809-1847) is familiar to every serious musician, and many of his works are familiar to everyone who has had any exposure to Western art music. He is mentioned at least briefly in every general music-history and music-appreciation textbook and is granted an article in all major encyclopedias of music. He has been the subject of numerous biographies, and most libraries' shelves include at least one of the many published collections of excerpts from his correspondence. His music was widely published during his lifetime, a collected works edition was issued already in the 1870s, and numerous further editions have been issued since then. On the face of it, these observations might suggest that the educated musical public's knowledge of Mendelssohn's life and works is reasonably well-founded. But this impression is misleading, for Mendelssohn remains an elusive figure. Much of his music and the vast majority of his letters remain unpublished; despite an impressive array of reliable editions published in the last few decades, most of the works that have been printed continue to be known primarily through corrupt or otherwise unreliable texts; and substantial quantities of other significant primary source materials have never been studied by scholars or considered in the biographical and critical literature. In short, the evidence on which most modern images of Mendelssohn are based is too limited to be considered representative. Latter-day observers may be familiar with the composer's name, (1) with some aspects of his biography, and with a small portion of his output, but in Mendelssohn's case as with other major composers such one-dimensional knowledge is necessarily discomfiting. Over the last few decades, a remarkable revival of scholarly and general interest in Mendelssohn and his music has been generated by a growing cognizance of the extraordinary quantity, breadth, and import of the primary documents of his life and works; this revival in turn has increased general awareness that conventional views of the composer and his historical significance have been shaped at least as much by specious music-historiographic polemics as by viable historical and aesthetic considerations. (2) But these developments have had little impact beyond the relatively limited circles of Mendelssohn specialists. Music history textbooks, music criticism, and the press in general offer little evidence of any broadened perspective on the composer's life, works, and historical significance. The present remarks propose that the key to a historically and musically viable view of Mendelssohn as composer and nineteenth-century cultural figure is the substantial corpus of little-known primary sources that document his life and work. I begin by exploring some salient developments in Mendelssohn's convoluted reception history, then summarize the historical and modern dispositions of the epistolary, chronographic, and musical primary sources. I conclude with some brief case studies in the insights offered by these documents and a review of some important developments in Mendelssohn research that have been occasioned at least in part by scholars' engagement with little-known source material. For convenience, appendix 1 offers a bibliography of significant Mendelssohn research published since the 1997 commemorative year. The notes in this essay are keyed to those entry numbers whenever possible. (3) PROBLEMS OF RECEPTION HISTORY The widespread acclaim Mendelssohn enjoyed during his lifetime derived in no small part from the compositions he published: seventy-two numbered opera, plus an additional twenty-four minor publications released without opus numbers. Yet it would be misleading to attribute his prestige entirely or even primarily to his efforts as a composer, for his reputation from about 1835 onward also derived from his contributions in other areas of musical endeavor. …