Yea Nuduke, I'm going through that now. I have mostly non-fiction spanning interests a over decades. They are reference materials for me. Many are marked with highlighter. I can't keep all of that information locked up in drawers in my brain. As it is needed, it tends to come back, but much has to do with applying old thought and concepts to new. I can go back to nearly any of these books and run through the highlighted areas where I studied before and long forgotten wheels begin to turn and I recall. Everybody forgets incredible amounts of info or tends to rearrange the reality of the time. I also often need to cite and get a more perfect recall. So, unless I intend to never again drop into some topic, I keep my reference. I've also got a less well organized library on my hard-drive and backup.
I love books, but more and more often, I'm finding easier access to the information on the internet. Still, More in-depth recall is best. Internet can not replace well read study.
I have kid books, too, within those are hopes for relived and tradition to pass on to grandchildren. I'm going to loose a lot of weight with those text books that were kinda irrelevant, but required, when I got my degrees.
Then, there's those that you pick up once in a while one afternoon every several years, like that Ferrarri photo book that once gave me an erection.

So, what about all of these National Geographics? What about those old 1948 Britannica that show how ignorant we once were, but also give scholarly detail which is less and less common?
Then, there's my collection of "N" Magazine, "Clothed with the Sun", going back to the mid-eighties, when I became a member. There is amazing scholarly nude information in those older issues edited by Lee Bauxendal. (spelled that wrong)
Jbee