How Michael Craig-Martin changed a glass of water into a full-grown oak tree 

‘Of all the things I’ve drawn,’ Michael Craig-Martin reflects, ‘to me chairs are one of the most interesting.’ We are sitting in his light-filled apartment above London, the towers of the City rising around us, and we are discussing a profound question, namely, what makes an object a certain type of thing? Or to put it another way, what makes a chair a chair?

Craig-Martin’s career has been characterised by what he calls ‘my object obsession’.