"A maester's raven flies to one place, and one place only. Is that correct?"
The maester mopped sweat from his brow with his sleeve. "N-not entirely, Your Grace. Most, yes. Some few can be taught to fly between two castles. Such birds are greatly prized. And once in a very great while, we find a raven who can learn the names of three or four or five castles, and fly to each upon command. Birds as clever as that come along only once in a hundred years."