An Oneirocriticon — the symbols of sleep, read across the traditions.
Every night, without asking, you are handed a message in a language you half-forget on the way to the kettle. Pictures that mean more than they show. A serpent in the water. A tooth coming loose. A house with a room you never knew was there.
This is the dictionary back into that language — and the long memory of everyone who ever tried to read it before you.