Beethoven could not copyright his music. Nor could he legally prevent other people from making arrangements of his music and publishing those. The only recourse Beethoven had was to request that his publishers reject the unauthorized arrangements.
On 13 July 1802, Beethoven wrote to the publisher Breitkopf & Härtel to thank them for doing precisely that: “As to the works to be arranged I am heartily delighted that you have refused them.” Then Beethoven complains about arrangements in general:
The unnatural mania, now so prevalent, for transferring even pianoforte compositions to stringed instruments, instrument which in all respects are so utterly different from one another, should really be checked. I firmly maintain that only Mozart could arrange for other instruments the works he composed for the pianoforte; and Haydn could do this too. And without wishing to force my company on those two great men, I make the same statement about my own pianoforte sonatas also, for not only would whole passages have to be entirely omitted or altered, but some would have to be added. And there one finds the nasty stumbling-block, to overcome which one must either be the composer himself or at any rate possess the same skill and inventiveness. I have arranged only one of my sonatas for string quartet, because I was so earnestly implored to do so; and I am quite convinced that nobody else could do the same thing with ease.” (Emily Anderson, ed. & trans., The Letters of Beethoven, pp. 74–75)
That one exception that Beethoven speaks of is an arrangement he made for string quartet of his Opus 14, No. 1, the Piano Sonata No. 9 in E Major (Day 107). In the process he transposed it to F Major to better fit the open strings of the viola and cello.
#Beethoven250 Day 154
String Quartet in F Major (Hess 34), 1801–2
No live performance seems to exist on YouTube of Beethoven’s own transcription for string quartet of his Piano Sonata No. 9.
Lewis Lockwood says that Beethoven’s Piano Sonata No. 9 “may have begun life as a string quartet and then became a piano sonata.” (Beethoven, p. 131) This might be why Beethoven was so agreeable to arranging it for string quartet, effectively returning it to its original state.