What's that knocking?

[buboe_the_rat]

Once upon a midnight dreary, while I pondered, weak and weary,
Over many a quaint and curious volume of forgotten lore,
While I nodded, nearly napping, suddenly there came a tapping,
As of someone gently rapping, rapping at my chamber door.
" 'Tis some visitor," I muttered, "tapping at my chamber door;
Only this, and nothing more."

...

From "the Raven" -Edgar Allen Poe