Key Concepts

This chapter introduces six key concepts related to formal organization of melodic sentences:

1. The Musical Sentence as Succession of Periods - The fundamental principle that sentences comprise successions of distinct periods organized around a central theme

2. Song-Sentence (Phrase Musicale) - A three-period structure with theme, middle period, and final period creating ABA' form

3. Commentary (Commentaire) - Melodic development of theme fragments through rhythmic, melodic, and harmonic variation

4. Binary Sentence - A four-period structure alternating theme and commentary in ABAB' pattern

5. Ternary Sentence - A five-period structure creating symmetrical arch form with central commentary flanked by thematic statements

6. List of Melodic Periods (Catalog of Historical Models) - Extensive catalog demonstrating transformation of diverse historical sources through Messiaen's compositional language