He must be thinking through the spells attached to the Index; he was having quaternary thoughts.

I thought it was anempty boast, but now I remember history texts describing ancient spells that could invest sleeping minds with quaternary thoughts.

She paused and then asked her next question in a softer tone: "Magister, have you ever had visions not related to quaternary thoughts?"

Quaternary thoughts change perception, not the world.

"You were having quaternary thoughts."