Some time in the heady sixties, I came across a poem by Artaud, which began, "All categories are shit". It was an anarchic phrase that haunted me for years. Even as I explained to a room of mildy interested students that they must abandon their personal observations of the world for the objective categories of sociological theory, I would have a sudden and disturbing image of Artaud throwing open the door and, in one bound, freeing my charges from the conceptual apparatus I was endeavouring to tie around their necks.