You take your rest after defeating the Lightwarden of Lakeland, and awake to a troubling development.
This quest is available if you have completed the quest Warrior of Darkness and have reached level 72.
Starting the Quest
Talk to the Manager of Suites to begin the quest.
Head to the Ocular
Use the Aethernet Shard to go to the Dossal Gate, then go east to the quest icon on the map. Talk to the Crystarium Gatekeep and say Yes to enter the Ocular. There will be a cutscene. This one is important, so it is recommended to watch it either now or via the Unending Journey in an inn room.
Speak with Moren
Check on the Exit to the Crystarium and say Yes to exit the Ocular. Go east to the Aethernet Shard and use it to go to the Cabinet of Curiosity. Go through the door and up the spiral staircase. At the top, talk to Moren.
Search the Shelves
Go to the lowest level of the library and go to the north side of the orange circle on the map. Check on the sparkling Towering Shelf there to find the book.
Deliver the Book
Go back up the spiral staircase and talk to Moren. Hand over The Illustrated Tale of the Oracle of Light. There will be a cutscene. This one is important, so it is recommended to watch it either now or via the Unending Journey in an inn room.
You can talk to Moren to re-read the book about the Oracle of Light or the book from an earlier quest about the history of Norvrandt.
Speak with Alphinaud
Go to the lowest level of the library and go south through the doors. Go to the quest icon on the map and talk to Alphinaud to complete the quest. There will be a cutscene.
Next Main Scenario Quest
After you complete the quest, talk to the Crystal Exarch to accept the next quest: The Crystarium's Resolve. There will be a cutscene.