Thesis (Ph.D.)--Boston University / This study presents a descriptive outline of the principal harmonic devices employed by Darius Millhard, Arthur Honegger, Francis Poulenc, Georges Auric, Germaine, Tailleferre, and Louis Durey. The emphasis is upon the particular techniques peculiar to each composer. In addition, all the characteristic mechanisms pertaining to the composer's harmonic idiom, per se, are isolated - i.e. technical analyses include those pertinent factors surrounding the usage of harmony as well as elements intrinsically peculiar to harmonic structure alone. The attempt is then made to relate the devices of the harmonic idiom to the significant movements in music at the time Les Six were producing most prolifically as a group. The role played by polyharmony, for example, in the trend towards privitism and divionism; or the relation of polymodalit to the general movement towards superposition, which was characteristic of the arts in the first quarter of the twentieth century. [TRUNCATED]