Theory

Music theory is the study of the structures of music as they are expressed in the musical score. It differs from fields such as music psychology and music cognition in that these fields are primarily concerned with the listener's perception and understanding of heard music. The discipline has traditionally considered issues of melody, rhythm, counterpoint, harmony, tonality, tuning, and form; although in more recent years, it has also addressed issues of performance, timbre, acoustics, improvisation, cognition and semiotics. Music theory simultaneously describes and proscribes what musical qualities are valued by the institution or culture that creates it.

Among the earliest theories regarding music in the Western world are those of Greek philosopher and mathematician Pythagoras, whose entire worldview was based around the principle that everything is related to mathematics, and that numbers are the ultimate reality. Although no actual writings by Pythagoras are known to have survived, some of his ideas concerning music are transmitted through other texts. He believed that the beautiful harmonies in music are the result of monochord string lengths in simple ratio relationship with each other. He favored the interval of the perfect fifth because its 3:2 relationship was the simplest ratio possible to produce a harmony. He also is said to have articulated a theory on the “harmony of the spheres,” which proposes that the planets and stars move according to mathematical equations and ratios that correspond to musical pitches, thus producing a form of celestial music. The earliest known theoretical writings dedicated to music are portions of Harmonic Elements and Rhythmics by the 4th century B.C.E. Greek writer Aristoxenus. Harmonic Elements is primarily a theory of scales and tonality that relies on experiential knowledge more than mathematical ratios and other empirical knowledge favored by other early Greek theorists who followed in the line of Pythagoras.

By the 2nd and 3rd century C.E., Greek writers such as Ptolemy and Aristides were creating a more systematic approach to music theory. Ptolemy viewed reason as a correlate to sensory experience, and concluded that it was not enough to merely observe a musical phenomenon; rather, it [Page 1122]was necessary to quantify it in some way. Ptolemy also considered music as one aspect of an interconnected universe, where everything exhibits similar principles of organization and codification. His three-volume Harmonics presents his thoughts on scale and tuning, as well as this relationship between music and the natural world. Aristides's Peri Mousikes moves from the pure theoretical to the practical by incorporating pedagogical and psychological aspects of music.