Speak with Ariane who is in the ruins beneath the Wizards' Tower. There is a dungeon link on the south east side of the tower. You must pass through two doors in the ruins before you reach Ariane. She will tell you she wishes to investigate the vortices further and requires your help. Accept and start the quest. Speak with Ariane again. She will tell you to use the runes to try and trigger a memory in the Library.