How about this quote from Stephen King’s Danse Macabre (h/t JustSell.com):
… talent is a dreadfully cheap commodity, cheaper than table salt. What separates the talented individual from the successful one is a lot of hard work and study; a constant process of honing. Talent is a dull knife that will cut nothing unless it is wielded with great force — a force so great that the knife is not really cutting at all but bludgeoning and breaking… Discipline and constant work are the whetstones upon which the dull knife of talent is honed until it becomes sharp enough, hopefully, to cut through even the toughest meat and gristle.