This achievement is story-based and should pop at the end of chapter two, when the screen fades to white after a long and kaleidoscopic dialogue sequence.
However, this didn't pop for me the first time through (if you regain control of Elea sitting in a chair and the achievement hasn't popped, you're in the same boat). I think the achievement for walking into the sphere three times can mess with this achievement, so you may have to restart the game to get one or the other. Getting back to this point should only take you about 20 minutes, though, so it could be worse.