I think Robin hit the nail on the head!
Another thing I might do is show your toddler one of the books he has torn or ruined. Tell him how sad it is that such a nice book was torn because it can no longer be read or because it looks ugly or whatever. Tell him we have to take care of our books to keep them nice.
When my kids were smaller, I would (in a half-disappointed voice) say something like, “Oh dear! Look at how you tore this page. How sad! We won’t be able to read this book anymore.” I would usually be met with big, teary eyes and a quivering bottom lip. A few times of that disappointment was all it took for them to begin taking better care of our things.
Blessings,
Lindsey