The letter collection contains 5,400 letters. The correspondents are primarily composers, musicians, critics, or music historians. The letters are composed in eleven different languages, with the majority being in French, German, and Italian. Throughout the collection, French is the predominant language.

Similar to the music manuscripts, Rudolf Nydahl acquired most of these letters through auctions or private contacts. When the extensive collection of Wilhelm Heyer, a German collector, was auctioned in 1927, Nydahl was among those who acquired a significant number of letters. In the early 20th century, many composer letters were also auctioned off to various music publishers. This allowed Nydahl to acquire correspondence addressed to publishers like Breitkopf & Härtel, Kistner, Peters, and more. This way, letters from prominent figures such as Haydn, Mozart, Beethoven, Mendelssohn, Chopin, Schumann, Liszt, Wagner, Verdi, Bruckner, Brahms, and Tchaikovsky ended up in Stockholm.

Letter from Wolfgang Amadeus Mozart to his father Leopold. Dated 1784.

The majority of the letters collected by Rudolf Nydahl were purchased in Paris. He amassed an impressive collection of French composer letters, with most of them acquired through auctions at Drouot. The collection includes letters from well-known French composers such as Fromental Halévy, Adolphe Adam, Charles Gounod, Jacques Offenbach, Camille Saint-Saëns, Georges Bizet, and Gabriel Fauré. The French letters are often related to the Paris Conservatory, the Grand Opera, or the Opéra Comique. Albert Carré (1852-1939), the former opera director of the Opéra Comique, had collected approximately 850 letters from French composers during his tenure. When he left his position, he took these letters with him, and Nydahl acquired all of them at an auction.

Among the world-famous singers featured in this letter collection are Jenny Lind, Christine Nilsson, Angelica Catalani, Henriette Sontag, Luigi Lablache, and Giovanni Battista Rubini. Renowned musicians include names like Clara Schumann, Teresa Carreño, Niccolò Paganini, Ole Bull, and Joseph Joachim.

It was more common to copy music manuscripts and attempt to sell them rather than doing the same with letters. However, such practices did exist, and thus, it was important to carefully examine the visual characteristics of the letters during cataloging. It was crucial to search for distinctive features in the handwriting, often unconscious to the writer. These features could include spacing between words and letters, how letters were connected, unusually high or low loops, the quality of the strokes (i.e., the pen’s pressure on the paper), and whether the handwriting was regular or irregular. Signatures were the most challenging to copy because they were written countless times and stored in the writer’s motor memory.

Most of the letters in German were not written in the ”standard” Latin script but in the German script, which dominated the German-speaking cultural area until the 20th century. Often, this script is difficult to decipher, primarily because it can be highly personalized. The most challenging letters are usually the capital letters, which can exhibit significant variations.

The collection includes a wide range of handwriting styles, ranging from highly balanced, calligraphic writing to more chaotic and difficult-to-read scripts. Below are two examples: a letter from Franz Berwald with easily readable German script and one from Robert Schumann with challenging handwriting. Many French letters can also be challenging to read, as they often seem hastily written, and the writers didn’t take much care in forming the letters. An example of this is a letter from Georges Bizet, one of the collection’s 100+ letters from him. Most of these letters were purchased directly from Bizet’s widow, Geneviève.

The catalog of the letter collection was published in 1999 by Bonnie Lomnäs under the title ”Catalogue of Letters and Other Documents.” It includes separate lists of all the correspondents and all the proper names mentioned in the letters.

Bonnie Lomnäs: Stiftelsen Musikkulturens Främjande (The Nydahl Collection) Catalogue of Letters and Other Documents, Statens musikbiliotek, Stockholm 1999, Musik i Sweden No. 11, ISBN 91-85172-07-3, ISSN 0077-2518. Price: 200 SEK + postage. It can be ordered here.

A checklist with the names of the senders can be found here.