Is that a real distinction? When Shakespeare is the 'most influential', then in some respects, he is setting what it means to be 'able'. He is setting our norms and expectations, laying down the language we think and write in. John Keats: "He has left nothing to say about nothing or any thing." Ralph Waldo Emerson: "His mind is the horizon beyond which at present we do not see."

When a writer is so influencing (should I say, 'distorting'?), is it really meaningful to draw a distinction between 'influential' and 'able'? Like Phil's implicit claim that every writer has an equal chance of being Shakespeare, this is not something I am willing to instantly grant without inspection.