The Bible is full of ridiculously common sense stuff. Some people still manage to use it as a tool to keep them doing those common sense things. That one doesn't strike my fancy, but I have some books that are similar for me.

It's so easy to understand a concept intellectually and yet fail to practice it on a day-to-day basis. Books can be a tool to refresh your thinking and get a (partially) objective point of view. A clear-thinking real person is almost always best, but books can be used in total privacy and on-demand.