Apparently a letter is received from Archduke Rudolph in Unterdöbling today, since Beethoven immediately writes a short note back saying he had already written a long letter yesterday, which his copyist Wenzel Schlemmer is delivering. Beethoven repeats that he had only heard of the arrival of Rudolph back in Vienna the day before yesterday, but the jaundice he is suffering from prevents Beethoven from appearing to wait on the Archduke in person and give his affection verbally.
[Perhaps because of disorientation due to his illness, Beethoven has trouble with the date. He first writes the 18th of July, then crosses that out and writes the 20th. Since he refers to the prior letter, which was dated the 18th, as “yesterday,” this letter appears to actually have been written on the 19th. Of course, it’s possible that letter is misdated as well.]
[Beethoven’s jaundice is apparently quite serious indeed. Except for one undated letter to the Archduke, there is after this no known correspondence or other documentation of Beethoven until the end of August, 1821.]