I used to think I knew quite a bit about history, but then I listened to a history professor lecture. It all pointed out the great chasm between what I thought I knew and actually didn't know. Of course there are many things I do, and I do well. But I have also watched people play the sports I've tried, or instruments I've played, and I have soon realized their understanding of it is many degrees higher than mine because their proficiency in it is way above mine.
