How does a politician – assassinated more than 50 years ago – gradually become a public figure? An extremely vibrant image which shows up where you least expect it. It served as figurehead for the Arab Spring revolutions, from Rabat to Sanaa, whereas we had thought it had been relegated to t-shirts and cigarette lighters. Why has this image become so universal that we are no longer surprised to find it in drawings, graffiti, tattoos and prints on all types of media in all sorts of contexts the world over? How can this image be used to advert...