After several years Beethoven once again turns to Friedrich Duncker (as in most cases he excuses his long silence on account of various illnesses). Duncker was the King of Prussia's cabinet secretary and had come to the Congress of Vienna with him in 1814, where he had met Beethoven. In spring 1815 Beethoven had composed the incidental music to Duncker's tragedy "Leonore Prohaska".
The reason for this letter is probably Beethoven's Missa solemnis op. 123 - people are only slowly replying to the call to subscribe. Beethoven gets in contact with Duncker, asking him to put in a good word for him with the King of Prussia so that he takes out a subscription.
