Claude Debussy (1862-1918) fundamentally changed how composers approached harmony, timbre, and form. His harmonic innovations—parallel chords, unresolved dissonances, and color-first compositional thinking—opened entirely new aesthetic possibilities that influenced generations of musicians across every genre. As a teacher and writer, Debussy advocated for direct musical experience over rigid tradition, believing students should develop their ears before absorbing rules.
Debussy's educational works emerged from this philosophy. Rather than dry technical exercises, pieces like Doctor Gradus ad Parnassum use genuine musical ideas to build pianistic and musical facility. These compositions reveal his conviction that learning an instrument should delight rather than merely train.