C.S. Lewis on Purpose

On the note of the post below:

Aim at Heaven and you will get Earth "thrown in;" aim at Earth and you will get neither. It seems a strange rule, but something like it can be seen at work in other places. Health is a great blessing, but the moment you make health one of your main, direct objects, you start becoming a crank and imagining there is something wrong with you. You are only likely to get health provided you want other things more - food, games, work, fun, open air. In the same way, we shall never save civilization as long as civilization is our main object. We must learn to want something else even more.

-C. S. Lewis, Mere Christianity (Chapter 10), 1952