Speaking from the perspective of a dark elf mage who has gone through every book shelf in Whiterun one click at a time — and that isn't a grouping of words anyone expects to write — the world of Elder Scrolls V: Skyrim is incredibly rich in detail. Bethesda has pages and pages of text in each virtual tome. Some unlock quests, some are just for fun, but all of them combined make up a huge chunk of text. If you actually want to / have the time read through it all, we might suggest this "Dovahkiin Gutenberg" compiled by capane.us.
Every word from the in-game Skyrim books are apparently accounted for here. Available in MOBI and EPUB formats, guaranteed to ruin a weekend or five. You should definitely pick up the game and play through a good chunk of it first, but then again, why else would you be reading this?