I know there's a reference in Cicero, perhaps to Torquatus but might be in Tusculun disputations, where he talks about the Epicureans memorizing his doctrines but it's referrred to as a "book" -- I think that's the "celestial book" referenced.
Edit: Looks like I am thinking about the book on the Canon being the "celestial" one, but I know also there is a reference in Cicero jibing someone about reading his book of doctrines.