The art of self-taught artists - including visionaries, folk creators, spiritualists, recluses, the 'mad' and the socially marginalized - was once scorned by the art establishment. Among the first to value and collect such works was the French artist Jean Dubuffet (1901-85), who coined the term Art Brut, or 'raw art'. He saw Art Brut as the purest form of creation because it was 'uncooked' by culture, touched by a raw nerve and deriving directly from...