He first recorded these fantasies in his Black Books. He then revised these texts, added reflections on them, and copied them in a calligraphic script into a book entitled Liber Novus
This passage defines the Black Books as the originary compositional stratum — the unrevised first-recording of active-imagination fantasies — from which Liber Novus was derived through deliberate interpretive elaboration.
, The Red Book: Liber Novus, 2009thesis