In Venice recently I was sitting in a cinema gazing at other people watching cinema. But I wasn’t a bored viewer checking out the audience around me. I was watching Shirin, the new feature film by Abbas Kiarostami, and the audience I was looking at was up there on the screen. The film begins with illustrations that summarise the story the onsceen ‘audience’ will be watching. It’s Khosrow and Shirin, an epic by the Persian poet Nezami, about a love triangle between an Armenian princess