We really teach ourselves. If you want to learn, you will always find someone to learn from, be they dead or alive, great or unknown. You learn from everything you see and hear around you - if you are willing to pay attention.
Many things are unknown to the wisest, and the best men can never wholly divest themselves of passions and affections... nothing can or ought to be permanent but that which is perfect.
The brank, or scold's bridle, was unknown in America in its English shape: though from colonial records we learn that scolding women were far too plentiful, and were gagged for that annoying and irritating habit.
If you fall in love with a woman, there's this unknown thing that gives you a force and energy, and music is like that, too. If I lived to be 2000, I'd never know anything about music. And that's great.
I've always been interested in the tension between knowledge and mystery, between science and religion, and the various ways we cope with the unknown. Some of those are productive; some can be attempts to pin down things that are by nature impossible to know.