When asked the question ‘What is art?’, Andy Warhol gave a characteristically flip answer (‘Isn’t that a guy’s name?’). On another occasion, however, he produced a more thoughtful response: ‘Does it really come out of you or is it a product? It’s complicated.’ Indeed, it’s those complications that make Warhol’s works compelling, as is demonstrated by a new exhibition at the Ashmolean Museum, Oxford.