Spoiler
Even barbarians and mindcrafters can learn spells, but not by reading books. They are able to use wands of wonder to gain a basic knowledge in the spell. After that, they can use the spellbooks to bookcast the spell. Costs shitloads of PP, though. And you still need to be literate ;)

By the way, I want to see someone creating an illiterate archmage...

Spoiler
The library is what I am talking about. Filled with books, thesauruses, tomes, scrolls, and all matter of preserved arcane knowledge. It is on the wilderness, about in the center of the map, a bit West from the main dungeon. It is only reachable by the rift, though, because it is enclosed by a ring of unclimbable mountains. A dungeon that requires you to climb/fall down a great rift. The rift can be found by walking past the fire tower, then a bit more W and NW. You need to be a certain level, and some other things to go there. So it is not for the lowlevels. Really it is not.

Spoiler
Use a pickaxe or a wand of digging downwards (direction '5'

Spoiler
You take a significant alignment drop, and you can dig up some seriously powerful, stat-draining, confusion-casting, help-summoning undead. I usually only do it when I'm absolutely desperate for a certain item. And even then, I do it very carefully (I prefer to have a means of teleportation to make a hasty escape). None of this applies to Griff's grave (except the alignment drop).