1. Pythagoras (c. 570 - 495 BCE): Pythagoras is considered one of the earliest pioneers in music theory. He studied the mathematical relationships between musical intervals and developed the concept of the Pythagorean scale, which is based on ratios of whole numbers. His work laid the foundation for the understanding of consonance and dissonance.
2. Ancient Greek Musicians (6th - 4th Century BCE): Greek philosophers and musicians such as Pythagoras, Aristoxenus, and Archytas made significant contributions to the theory of harmony. They explored the use of scales, intervals, melodic structures, and the concept of ethos (the emotional impact of music).
3. Guido of Arezzo (c. 995 - 1050 CE): Guido of Arezzo was a Benedictine monk and music theorist who is often credited with developing solmization, a system of using syllables (Do, Re, Mi, Fa, Sol, La) to represent musical notes. This system played a vital role in the teaching and understanding of harmony in Western music.
4. Johannes Tinctoris (c. 1435 - 1511): Tinctoris was a Flemish composer, theorist, and music educator. He wrote several treatises on music theory and harmony, including "Liber De Arte Contrapuncti" (Art of Counterpoint), which discussed harmonic principles and contrapuntal techniques.
5. Josquin des Prez (c. 1450 - 1521): Josquin des Prez was a Franco-Flemish composer who is considered one of the most influential composers of the Renaissance period. He contributed to the development of harmonic complexity in polyphonic vocal music, showcasing advanced chord progressions and voice leading techniques.
6. Jean-Philippe Rameau (1683 - 1764): Rameau was a French composer, music theorist, and organist who is known for his contributions to music theory, particularly in the area of harmony. He published "Traité de l'Harmonie" (Treatise on Harmony) in 1722, which presented his theory of harmony based on the concept of the fundamental bass.
7. Johann Sebastian Bach (1685 - 1750): Bach, one of the greatest composers of the Baroque period, advanced the art of harmony to unprecedented levels. His music demonstrated deep understanding and use of harmonic principles, complex chord progressions, and intricate voice leading, particularly in his polyphonic works, such as the "Well-Tempered Clavier" and various fugues.
8. 19th-Century Classical and Romantic Composers: Throughout the 19th century, composers like Ludwig van Beethoven, Franz Schubert, Frédéric Chopin, and Johannes Brahms continued to push the boundaries of harmony, exploring new harmonic possibilities and expanding the tonal language of Western music.
The development of harmony was not solely attributed to a single person, but rather a collective effort and evolution of musical ideas over centuries. Numerous musicians, theorists, and composers contributed their knowledge, creativity, and innovations to shape the art of harmony we have today.