Who's In The Next Room?

"Who's in the next room? - who?
I seemed to see
Somebody in the dawning passing through,
Unknown to me."
"Nay: you saw nought. He passed invisibly."
"Who's in the next room? - who?
I seem to hear
Somebody muttering firm in a language new
That chills the ear."
"No: you catch not his tongue who has entered there."
"Who's in the next room? - who?
I seem to feel
His breath like a clammy draught, as if it drew
From the Polar Wheel."
"No: none who breathes at all does the door conceal."
"Who's in the next room? - who?
A figure wan
With a message to one in there of something due?
Shall I know him anon?"
"Yea he; and he brought such; and you'll know him anon."