Probably the most treasured item I own is a novel a good friend of mine gave me as a gift. It was one of their favourite books, and they'd highlight lines and sections that resonated with them by putting brackets around them using a pen. Coming across those sections, and learning a bit more about them in the process, is like finding little nuggets of gold.

But I get where you're coming from as well. I guess it just really depends on the context of who/what/why when it comes to reading.