[ Castiel pauses, touching his face as if to check whether or not he does, in fact, have a beard. He doesn't - despite being trapped in an apocalyptic winterscape for months at this point all he's managed to accrue is some impressive stubble. ]

The Book of Honorius was composed around... [ He pauses, doing some quick mental math. ] The thirteenth century by the Gregorian calendar. The Vessel I inhabited at the time had a beard. His appearance may have left an impression upon the author. I've never ridden a dragon, though. They're temperamental, and much slower than angels in all regards. Whoever wrote that down must have been confused.

We're getting sidetracked. Do you or do you not know the Language of the Birds?