
This book changed the way I think about what is right and what is wrong.
The answer comes back: "To become something that is not man."
Extinction itself isn't really anything to be scared of. The real question is whether we're replaced by something better, and maybe what those superior beings would think of us after we're gone.
(That last question is answered in one of Stephen Baxter's books with: "an extremely successful animal that enlarged its ecological niche")