The letter was a love letter, ten pages long, and it was addressed to
link his "Immortal Beloved." Beethoven never sent the letter, and today there is still considerable speculation as to whom the intended recipient might have been. Fidelio is, of course, the name of Beethoven's
link only opera (I just discovered that the original title was supposed to have been Leonore,
link Or The Triumph Of Marital Love, and you gotta admit that Fidelio has a bit more punch) which was first performed in 1805.
link