Early in the autumn of 1994, the first tome of Olivier Messiaen’s vast Traité de rythme, de couleur, et d’ornithologie was published posthumously by Alphonse Leduc in Paris.2 The following six tomes appeared at regular intervals up to 2002. The publication was a highly anticipated event. As early as 1949 Messiaen began compiling notes concerning various aspects of rhythm, an element of musical discourse that fascinated him as much as a composer as in his capacity as professor at the Paris Conservatoire, where he taught from 1941 to 1978. Over the years, the project grew to incorporate large sections devoted to birdsongs, modes and harmonic colours, as well as analyses of excerpts from the repertoire and of some of his own compositions. The entire treatise comes to over 3,200 pages divided into seven tomes, the fifth of which is published in two separately bound parts.