[leoedin]

You almost certainly can't teach whatever it is that makes a great artist great. Just like you can't really teach the mindset and thought processes that make a great engineer great. But you can teach techniques, and you can encourage practice of the craft, and teaching exposes people to ideas that they might not be aware of otherwise.

Good teaching is very rarely "this is a fact you must memorise", but putting the right environment in place for someone to do something themselves. If someone goes to art school, has a class on pottery, learns how to use the wheel and the kiln, and then becomes a renowned potter, did they learn that at school? Probably not the part where they became renowned - but the school did provide them with the tools to get there.