When Heinrich Ströbel commissioned Olivier Messiaen to write a new piece for the Donaueschingen Festival, he took care to specify that the piano and the ondes martenot were to be strictly forbidden. (‘Attention, Messiaen! Cette-fois-ci, pas d'onde, pas de piano!’) Such a specification is liable to be read as a measure taken to guard against any possible revival of the sound-world of Turangalîla-symphonie (1946–8). In an effort to surpass the achievements of Turangalîla, however, Messiaen had moved rapidly and decisively in the intervening years. Brief periods of teaching at Darmstadt and Tanglewood led to an obvious surge of experimental works, followed by Réveil d'oiseaux (1953), Oiseaux exotiques (1955–6) and Catalogue d'oiseaux (1956–8), his first attempts at composing primarily with bird songs. With the completion of Chronochromie (1959–60), the aesthetic stance of most of the ensuing works was firmly in place.