The Great God Om

A fragment from Small Gods by Terry Pratchett:

The Brutha boy was flat on his face in front of a statue of Om in His manifestation as a thunderbolt, shaking and gabbling fragments of a prayer.

There was something creepy about that boy, Nhumrod thought. It was the way he looked at you when you were talking, as if he was listening.

The protagonist, Brutha, is a novice living at the Citadel, a giant fortress/monastery sort of thing. He has just been accosted by a talking tortoise in the garden, the latest manifestation of the Great God Om, although not recognized as such. The tortoise didn't say much of anything, but it bothered him. Brother Nhumrod is his novice master, and generally a strange, slightly demented guy. Nhumrod tries to explain to him about hearing voices, which doesn't especially help.