Her library would have been valuable to a bibliophile except...

Her library would have been valuable to a bibliophile except she treated her books execrably. I would rarely open a volume that she had not desecrated by underlining her favorite sections with a ball-point pen. Once I had told her that I would rather see a museum bombed than a book underlined, but she dismissed my argument as mere sentimentality. She marked her books so that stunning images and ideas would not be lost to her.