It's odd, with me. Though I obviously can't forget that I've read the book, or the things which made such an impression on me (just as it is also obvious that many details will slip out of one's memory), I nonetheless attempt to do something very similar, and approach most re-reads (there are a few exceptions) "with new eyes", without preconceptions interfering too much with my reading. As a result, I often come away from a re-read with quite a different feeling, or gathering an entirely new set of impressions, which I have almost never done when going in with such preconceptions... save that, in the latter case, it can diminish my enjoyment on occasion.
Yep, there's that, too. Whilst ideally, I would like to die having just finished the last of my books that day, I would rather have unread ones on the shelves than to not have anything new awaiting me. After all, I don't know how long I'm going to last -- today? tomorrow? or (with medical advances) 150 years from now? -- and having even the possibility of some new gem I've not yet read waiting to be discovered, a new favorite to which I would return again and again if I am allowed that time... that, to me, is a much better situation. I don't ever want to stop learning or discovering new things; any more than I want to stop re-exploring or re-examining the old.
And, as Steve says, leaving behind such treasures for those I love, so that they, in turn, can make such discoveries, and perhaps pass them on to those they love in turn... Well, I've a book on my shelves which was printed in 1699, and the sheer thought of all the history it has seen, all the hands it has gone through, all the people who have read it in that time, is a fascinating and stimulating thought to me, and if some of the things I've acquired can have that effect on others... that, too, is a pleasing thought.
I always thought that I would never have the time to re-read books, but when I gave up work and couldnt buy as many, those old favourites came in handy -LOL
