altered books

i really just don't understand this concept of altering books. I think I mainly have a problem because I feel like a book is something complete, sacred.... and glueing all over it takes away its ability to pass its knowledge set (words). I understand it's supposed to be a sort of art form and personal expression, and man, I'm all about that... but I don't know if I could alter a book... it just seems uncomprehensible to me.

don't know what I'm talking about?

see a few links:

linky 1 -- images

linky 2 -- talks about taking an "unwanted book" but what if someone else could gain from the book? i just feel so uncomfortable thinking about taking away that possibility.