Seven Doors and Forty-two Keys

Seven Doors and Forty-two Keys is a book by Piers Russinol.

The book was one of the works Mr Norrell kept secluded in his library at Hurtfew: evidently it was among that large body of literature he decided his pupil Mr Strange might not yet be ready to read. When the two become immured together in the Pillar of Darkness however, and are briefly noticed by the Raven King, the Russinol is transformed for a second or two into a raven. When it again resumes its usual shape Strange picks it up and reads the passage at random, purely so Mr Norrell can be assured that the books have not been harmed by their alteration:

"...and there you will find a strange country like a chessboard, where alternates barren rock with fruitful orchards, wastes of thorns with fields of bearded corn, water meadows with deserts. And in this country, the god of magicians, thrice-great Hermes, has set a guard upon every gate and every bridge: in one place a ram, in another place a serpent..."[66]