I once met an aristocratic woman who had trepanned herself. In her moated Tudor manor outside Oxford, as an African Grey parrot nibbled her ear, she showed me the film she had made of the procedure. She shaved her hairline, bandaged her head, put on dark glasses and a floral shower cap, peeled back a patch of skin with a scalpel and applied the point of a dental drill to her frontal bone. A few minutes later its grinding teeth made it through the dura mater, releasing a geyser of blood. As it gurgled from the half-centimetre opening, she smiled, blood dribbling between her teeth.