Sequentia cyclica

Sequentia cyclica super "Dies irae" ex Missa pro defunctis (Ecclesiastical Latin: Cyclical Sequence on 'The Day of Wrath' from the Mass for the Dead), commonly known as Sequentia cyclica (Cyclical Sequence), is a piano composition by Kaikhosru Shapurji Sorabji. Written between 1948 and 1949, it is a set of twenty-seven variations on the medieval sequence Dies irae and is widely considered one of Sorabji's greatest works. With a duration of about eight hours, it is one of the longest piano pieces of all time.