What are the ingredients that enable an artist to be a master above all other masters?

On 6/2/2011 I saw the product of one such master at the Cultural Arts Center of Glen Allen’s “Folkways . . . Master Artists of Virginia” exhibition: the #7 hand-built guitar by Wayne Henderson, “the first one I sold for much money,” ($500 in 1968). (The exhibition also has quilts, decoys, baskets, and other hand-crafted artworks.)

If you’ve read that great book by Allen St. John – Clapton’s Guitar – you know all about Wayne Henderson, how he builds guitars, and the fact that they are globally special. And you know that Wayne’s guitars are works of art whose tonal quality is unsurpassed.

What qualities need to be in place to enable an artist to be not simply “good enough” – but to transcend all notions of comparability with other artists within the same discipline?