Your question--and Teller's advice about the arts--dovetails with Bret Victor's excellent talk, Inventing on Principle, recently released from CUSEC [1]. He starts by blowing you away with demos of software he's built, but then he backs up and reviews how he got there and why. His self-discovery process involved trying, making, and experiencing lots of things over a difficult period of ten years. That process eventually gave him the perspective to find commonality in things that make him react strongly. From there he found a principle to live by. For Bret and other examples he cites, it's not about domains and returns. It's about having a distinctive principle or cause that guides your decisions and approach to domains.

See also: mbarnett's response. I can't say it better than that.

1 - http://vimeo.com/36579366