Swedish composer Claude Loyola Allgén (1920-1990) is one of the most enigmatic characters in the history of Swedish music. An intermittent member of the so-called Monday Group in the 1940s (alongside for instance Ingvar Lidholm), he received instruction from Karl-Birger Blomdahl and Hilding Rosenberg. Both as a composer and as a person, Allgén was highly original, however, and came to lead a very isolated existence. Born Klas-Thure Allgén, he changed his name upon his conversion to Catholicism in 1950. Even though his plans to become a priest came to nothing, his spiritual quest would continue to inform his music to a great degree. Living the life of a recluse he remained outside the circles that would normally have contributed to his music being performed and published, and at his death in a fire, a part of his musical manuscripts were destroyed. The surviving works have a reputation for being unplayable and are often distinguished by their great length and complexity.