Henri Dutilleux is one of the most important French composers of the second half of the 20th century, producing work in the tradition of Maurice Ravel, Claude Debussy, and Albert Roussel, but in a style distinctly his own. Although his output is relatively small, its high quality and originality have won international praise. Some of Dutilleux's trademarks include very refined orchestral textures, fluid and intricate rhythms, a preference for atonality and modality over tonality, the use of pedal points that serve as atonal pitch centers and "reverse variation" by which a theme is not exposed immediately but rather revealed gradually, appearing in its complete form only after a few partial, tentative expositions. His music also displays a very strong sense of structure and symmetry. This is particularly obvious from an "external" point of view i.e. the overall organisation of the different movements or the spatial distribution of the various instruments but is also apparent in the music itself (themes, harmonies and rhythms mirroring, complementing or opposing each other). Most of his works have a dreamlike, highly poetic quality, which makes them relatively more accessible than those of many other post-World War II composers.