Nitsch is notorious as the ‘action artist’ whose controversial performance artworks from the 1960s onward have included the use of blood, dismembered animals and so on. His explorations of multiple media include music, and his reverence for Bruckner as a composer whose works symbolize the expression of a multifaceted cosmic soul of some kind seems entirely genuine and sincere. His organ piece is a good deal less controversial than many of his performances; it consists of a slowly evolving succes…