The impressionism of Debussy is achieved through a number of means the overall aim of which were to weaken the teleological (Purpose driven) harmonic structure of classical (functional) western harmony. In functional harmony a path is set that leads inexorably to a final cadence at which the tonic is clearly affirmed, dissonance whether through the use of suspensions or 7th chords etc. is correctly prepared and then resolved creating a flow of tension and release. By contrast, many of Debussy's dissonances simply flow onto another dissonance in chains of seventh chords etc. Another way that Debussy holds tonality in suspense is through the use of the pentatonic and whole-tone scales in both melody and harmony. The story of modernist music has been a response to the extreme chromaticism of radical romantic composers such as Wagner and Liszt. The ones who felt compelled to complete the task took music to the chromatic extreme of atonality, others found ways to continue to write music using recognisable harmonic sequences and tonal (therefore recallable) melody by emancipating the dissonance and freeing it from its functional straightjacket. Debussy played a massive part in developing the vocabulary for this kind of composition. All non-atonal composers of the modernist era owe a debt to Debussy, including Stravinsky, Bartok, Messiaen and possibly even Steve Reich.