Some books actually defy grade level classification, like L'Engle's A Wrinkle in Time. I re-read it this year and I think there are references I would still need to look up. But you don't have to understand every nuance of a book to enjoy it.
All of this talk about vocabulary got me wondering if there is some hard core vocabulary test where you are given two words that could be used interchangeably but you have to explain how they are different.
Anyway, the words you need you will learn as you need them. Just like you always have. I probably didn't learn 'juxtapose' until college where it became a basic part of my art criticism vocabulary. (Put one thing next to something else.)
