Lost for words

I started reading F. Scott Fitzgerald's This Side of Paradise last night. I've owned my copy for a decade and a half at least and, judging by the state of it, have definitely read it a few times. But I couldn't remember a single word of it. Weird. And it's great - really insightful and amusing. How could I have forgotten it so completely? Has it just been buried under an avalanche of other novels over the years?

I have a lot of books - thousands, probably. I find it impossible to throw away even the ones I haven't particularly enjoyed. Now I'm looking at my bookcases and wondering how many other novels up there have been wiped from my memory banks. All least I'll never run out of good books to read...