Carl Jung was a famous 20th century psychologist, the founder of the Analytical Psychology movement. He was a student of Freud’s, though he later diverged from Freud’s theories. It was during this time that he began work on what was formally titled Liber Novus, but was known informally amongst Jung’s followers and heirs — and eventually published — as The Red Book.
The book had its beginnings in what seemed to be a psychotic breakdown for Jung, starting in 1913. Jung himself referred to the period as a confrontation with his own unconscious. He worked on it for 16 years, while developing his own psychological theories. The contents in the book were produced by using a technique of Jung’s own development that he called “active imagination”, wherein he was visited by a male and female figure, whom he later identified as the prophet Elijah and Salome, who guided him through the process of delving into a collective unconscious.
Jung’s heirs kept the Red Book from being accessed for nearly eighty years, until 2001. It was finally published in 2009.