The Book of Oa is a massive book held in the Citadel of Oa. Created long ago, the Book contains the history of the Guardians of the Universe and the Green Lantern Corps. One member of the Green Lantern Corps is selected by the Guardians as Keeper of the Book of Oa, a highly honored position. After Thomas Kalmaku used Jordan's ring to rebuild Oa, Kyle Rayner used his power as Ion to resurrect the Guardians. The Book of Oa is now restored. The Forbidden Chapter of the Book told the prophecy of the Blackest Night, the final destruction of the Green Lantern Corps at the hands of their greatest enemies as it was told to Abin Sur by the demons of Ysmault.