In 〞Technique of My Musical Language〞, Olivier Messiaen clearly presents his personal interest in 〞time〞 and 〞rhythm.〞 They are perfectly treated in his 〞Quatour pour la Fin du Temps〞, which was written in a prisoner-of-war camp of the German army during the Second World War. In addition to rhythm, the particularity of Messiaen's music consists of his treatment of harmonic color and orchestral timbre. Messiaen's 〞Chronochromie〞 presents both the elements 〞time〞 and 〞color,〞 wholeheartedly. As a teacher, Messiaen inspired a number of musicians in his famous class of 〞Musical Analysis and Aesthetic〞 at the Conservatoire of Paris. In the 1970's, two of his pupils, Gérard Grisey and Tristan Murail, established and developed the 〞Spectral School,〞 which has succeeded his interests in time and color and inspired many young composers. First, our research will focus on the discourses of Messiaen and Grisey regarding time and rhythm in reference to Messiaen's last theoretical work, Traité de Rythme, de Couleur, et d'ornithologie, and Écrits ou l'Invention de la Musique Spectrale of Grisey. By introducing the ideas of Messiaen and those of Grisey, we will attempt to determine the relationship between 〞spectral music〞 and the ideas of Messiaen particularly in the domain of time and rhythm. Finally, we will try to find the intricate evolutionary process from Messiaen to s 〞Spectral School〞 in the context of contemporary French music.