Explain why action-reaction forces do not cancel each out

I "love" these sorts of questions ...

Book on a table. Book presses down on table as the action. Table reacts by pressing up on book. So, the forces are on different objects.

Object colliding with, a very heavy obstacle such as a brick wall. Object presses on brick wall. Action. Wall presses back on object. Action - Reaction equal and opposite and on different things. So, object gets a "recoil impulse of force" from wall and bounces off". Wall gets a "recoil impulse of force" and hardly moves 'cos of its much bigger mass (which is why I chose it for the example).