Deep truths are often hidden from conscious thought.

Yet their influence moves through your imagination when you’re not paying attention.

In this way, we can gain glimpses of insight that are quite useful to our daily lives. Essentially, you get a feeling that you “know something,” but without knowing exactly why.

That knowing comes from processing ideas and mental associations at a volume far too great to hold in conscious thought.

When you take a shower, wash the dishes, or drive home while listening to music, your mind may be processing a problem even though you have let go of the conscious effort of deliberate thought.

Your mind wanders into what neuroscientists have begun calling “the default network.” It’s a mode of thinking based in imagination, discovering loose associations, and processing nuances of your social world.

The number of associations your brain crosschecks against other ideas, hopes, fears, dreams, and imagined scenarios is so...