Final answer:
Arnold Schoenberg abandoned the principle of tonality by experimenting with atonality and creating music without a central, binding key.
Step-by-step explanation:
Arnold Schoenberg, an Austrian composer, is known for his experiments with atonality and the invention of the twelve-tone scale. He abandoned the principle of tonality by creating music without a central, binding key. Schoenberg deliberately subverted traditional musical expectations by incorporating dissonance and unexpected notes in his works. Mahler's contributions to music were critical, serving as a bridge between the Romantic era's expressive tonality and the modernist explorations that followed. His ability to blend the old with the new created compositions that, while rooted in tonal music, expanded the listeners' horizons and paved the way for more radical departures from tonality by other composers, like Schoenberg.