The Book of Lies was a Faction Paradox dynabook. Since its textual generators were directly interfaced to the unstable nature of reality, it was different in numerous subtle ways each time it was opened. Unlike most religious texts, the Book of Lies says how the universe isn't rather than how the universe is. Its stories were combinations of detailed alternative histories, scandalously rewritten versions of historical events, fractal poetry, ominous foreshadowing, and historical truth.
The library on Dellah contained a copy of the book.
One such story told of "Life" returning to Gallifrey after ten million years of winter and drawing the scorn of the Great Grey Eminence sleeping in his tomb. Since the Eminence wanted to get rid of passion from his sterile world, he made a deal with the Devil to "make things unhappen". The Devil's minions changed everything back the way the Eminence wanted, and they took the one who brought Life back and folded his timeline back on itself. But the Devil did it for his own reasons, since he wanted to teach the Eminence the ways of Paradox.
Another story apparently described the boy returning to the Eleven-Day Empire and the Mothers and Fathers of Faction Paradox pronouncing his work on the Eighth Doctor to be inelegant but beautiful, with fractal possibilities leading to glorious recursion. Threads that had appeared in the Doctor's history several regenerations ago were tying together, and his desires to abandon his past and upset the establishment made him an ideal candidate for the Faction. However, they noted that he was less interested in the beauty of the pattern than in one girl's life.
However, the Book went on to say that these events had never happened. This disclaimer was a frequent refrain in the Book. The text went so far as to occasionally speculate that it was itself a hoax, even including a section of Watkinson and Thripsted's Introduction to Quantum Esotericism that discusses the Book's unreliability. In the sampled section, the authors speculate that the Book is not actually secret but instead intended for a non-Faction audience as a way to introduce them into the Faction's deconstructivist way of thinking.