Paul Graham, a programmer and writer, has written an article about your “top idea.” He discusses the the concept of what he calls “ambient thinking” or those thoughts you have when you’re in the shower. Graham makes an interesting point that the idea that has dominance over your mind dictates the other types of thoughts you can have.
Graham makes an observations about thoughts to avoid that are particularly poignant from a Christian perspective.
I’ve found there are two types of thoughts especially worth avoiding—thoughts like the Nile Perch in the way they push out more interesting ideas. One I’ve already mentioned: thoughts about money. Getting money is almost by definition an attention sink. The other is disputes. These too are engaging in the wrong way: they have the same velcro-like shape as genuinely interesting ideas, but without the substance. So avoid disputes if you want to get real work done.
It is worth noting that thoughts of money and disputes are the types of thoughts that Graham says detract from correct thinking. For the Christian, the areas of provision and forgiveness are where our thoughts and fears can dictate how we respond to the world. The article is a worthwhile read.