Find and collect all 5 volumes of A History of the Living Lands to unlock the Historian achievement. The first 4 volumes are found inside the Eothasian Temple. The 5th and final volume is located just outside the temple, but it can only be reached from inside.
A History of the Living Lands I: Origin
The first book is located near
Caedmon as you are progressing through the Dawntreader questline. From Caedmon, continue on the main path and hug the right wall. Destroy a small barrier that leads into a chamber next to the NPC and collect the first volume.
A History of the Living Lands II: Lacuna
When you reach the large room with the
statue, climb the statue and jump to the platform beside it. Turn around and jump to the back of the statue and then to the ledge on the far side of the room. Go over the wall, through a crawl space, and jump the gap. Follow the path outside while ascending platforms while hugging the right wall. Collect the second volume in the room at the top.
A History of the Living Lands III: Glossolalia
As you enter the
library, look straight ahead and jump to reach the third volume on a door frame.
A History of the Living Lands IV: [Redacted]
While facing the altar with the
relic, look down and to the right. Crouch down (
) and destroy the post on the right. Follow the blue path and collect the fourth volume of A History of the Living Lands.
A History of the Living Lands V: Synthesis
From the statue, take the
elevator back up to the surface. Inside the bedroom, look behind the large bookshelf on the left side. Collect A History of the Living Lands V.