The Dies Irae theme, a piece of Gregorian chant attributed to Tommaso de Celano (1200-1260), remains familiar from its appearances in later music, notably in the works of Rachmaninov and the finale of Berlioz’s Symphonie Fantastique. The solo piano work Sequentia Cyclica by Kaikhosru Shapurji Sorabji (1892-1988), recorded here for the first time, consists of 27 variations on that well-known theme.