* The book gave us the NightmareFuel that Vorbis has spent an eternity in a hell of his own making. But why? Because he's in the desert, and he's absolutely alone. He knows it, there can be no doubt, that he is all alone. But he still hears the voice of Om. Because it's his own voice and always has been. The worst HeelRealization ever.
* Everyone in the desert is alone because they believe they have to face it alone. Brutha's seen the desert, and he knows they're not alone, and he knows Om will be there with them. Except for Vorbis, so Brutha's there for him, the only one who needs him.
* Om took the form of the tortoise because at the time all true belief that Omnians had was in the Turtle. That it moves. They didn't exactly believe in Om, but they still considered themselves his worshipers and thus gave him this form.
* Brutha can't read, yet carrying around the contents of the Library causes some of the information written in them to "leak" into his awareness. This ''could'' mean that he's finally starting to grasp how writing works, but it could also mean that he's become host to an entirely-mental version of a "tomb of words", like the Post Office from ''Going Postal''. He's not reading the books, they're ''talking'' to him--and he's ''listening'', the same way he was noted to ''listen'' to others talk earlier in the book.
* After ''Thief Of Time'' revealed that Brutha's story played out over a century ago from the rest of the world's perspective, the recent increase in Omnian missionary activity in the Ankh-Morpork books makes a lot more sense: Brutha's endorsement of the "Turtle Moves" belief must have seemed to be vindicated when the entire Disc, Omnia included, witnessed the baby world-turtles hatching in ''The Light Fantastic''. Indeed, that event could be what initially kicked off the flood of schisms that beset the Omnian faith for so many years afterward, that culminated in Mightily Oats's internal conflict in ''Carpe Jugulum''.