Mauricio Kagel (born in Buenos Aires, December 24, 1931, died in Cologne, September 18, 2008) was an Argentine composer who has lived in Germany for most of his career. He was most famous for his interest in developing the theatrical side of musical performance. Many of his pieces give specific theatrical instructions to the performers, such as to adopt certain facial expressions while playing, to make their stage entrances in a particular way, to physically interact with other performers and so on.
Sir Michael Kemp Tippett, O.M. (2 January 1905 – 8 January 1998) was one of the foremost English composers of the 20th century. Tippett was regarded by many as an outsider in British music, a view that may have been related to his early conscientious objection and his homosexuality. His pacifist beliefs led to a prison sentence in World War II, and for many years his music was considered ungratefully written for voices and instruments, and therefore difficult to perform.