Temperance and sneaky idols

I'm planning C.S. Lewis curriculum at the moment. (Yes, I'm teaching a class on C.S. Lewis in the fall. My job is that awesome.) In the midst of reviewing Mere Christianity I came across this gem of a paragraph:

One great piece of mischief has been done by the modern restriction of the word Temperance to the question of drink. It helps people to forget that you can be just as intemperate about lots of other things. A man who makes his golf or his motor-bicycle the centre of his life, or a woman who devotes all her thoughts to clothes or bridge or her dog, is being just as 'intemperate' as someone who gets drunk every evening. Of course, it does not show on the outside so easily: bridge-mania or golf-mania do not make you fall down in the middle of the road. But God is not deceived by externals.

An idol may not be-- in fact is probably not-- externally obvious.