Music existed for thousands of years before anyone wrote it down. Ancient Greek philosophers theorized its mathematical basis. Medieval monks created the first notation system. This is where Western music begins.
Music precedes written history by an enormous margin. Archaeological evidence of organized musical activity extends back at least 40,000 years: the bone and ivory flutes found at Geißenklösterle in southern Germany are dated to roughly 43,000 years ago, and the vulture-bone flute from nearby Hohle Fels to about 40,000 years ago; both have deliberately cut finger holes. Cave paintings at sites across Europe include figures that appear to be in dancing postures, suggesting organized movement to rhythm. The Divje Babe flute, found in a cave in Slovenia and dated to approximately 60,000 years ago, remains controversial — some scholars argue the holes were made by bear teeth rather than human intention — but the preponderance of archaeological evidence suggests that music-making is among the oldest human behaviors, predating agriculture, pottery, and written language by tens of thousands of years. What drove this impulse is not recoverable; theories range from sexual selection to social bonding to cognitive development. What is recoverable, beginning around 2000 BCE, is a written record of music's role in ancient civilizations, and with that record begins the history of music as a documented tradition.
In ancient Greece, music occupied a position that no subsequent European civilization has precisely replicated: it was simultaneously a branch of mathematics, a form of ethics, and a technology of civic life. Pythagoras, working in the sixth century BCE, discovered that the fundamental musical intervals — the octave, the perfect fifth, the perfect fourth — correspond to simple integer ratios: a string half as long produces a pitch exactly one octave higher; a string two-thirds as long produces a perfect fifth. This discovery, made empirically by measuring the vibrating lengths of strings, revealed that musical experience had a mathematical structure underlying its sensory immediacy, and Pythagorean philosophy built from this discovery an entire cosmology in which numerical ratios governed the movements of the planets as surely as they governed musical consonance — the so-called Music of the Spheres. Plato, writing in the fourth century BCE in the Republic, argued that the musical modes taught to children had direct moral consequences: the Dorian mode instilled courage and discipline; the Lydian mode produced softness and effeminacy. His proposals for the musical education of the ideal state's citizens were prescriptive and restrictive — certain modes and instruments were to be banned as morally dangerous. The seriousness with which Plato treated the ethical dimension of musical experience reflects a cultural consensus about music's power that Greek civilization maintained consistently.
The music that the Greek philosophers were describing is almost entirely lost; the notation systems they developed were incomplete and the surviving fragments, while decipherable in pitch, cannot be reconstructed in rhythm or performance practice with confidence. The Western musical tradition as a continuous and recoverable practice begins with the Christian Church and specifically with the body of liturgical chant that became systematized between the fourth and ninth centuries CE. Gregorian chant — named after Pope Gregory I (590-604 CE), who is credited by tradition with organizing and standardizing the liturgical repertoire, though modern scholarship suggests his direct role was more limited than legend claims — is monophonic: a single unaccompanied melodic line, sung in unison, without harmonic support or metrically regular rhythm. The melodies move stepwise within modal scales (not the major-minor system that would come later), and the texts are predominantly Latin liturgical prose, the melody flowing in a rhythm determined by the natural stresses of the words. Gregorian chant remained the foundation of Western liturgical music for five centuries and exercised a shaping influence on the harmonic language that followed long after it ceased to be dominant.
The decisive technological development that made Western music's subsequent history possible was the staff notation developed by the Benedictine monk Guido d'Arezzo (c. 991–after 1033). Before Guido, music was transmitted largely orally, with neumes on the page serving only as reminders of melodies already learned: new monks learned chants by hearing them from older monks, a process that was slow, error-prone, and geographically limited. Guido developed the four-line staff — an arrangement of horizontal lines at specific pitch intervals that allowed individual notes to be precisely specified — and a syllabic system for teaching sight-reading that assigned the syllables Ut, Re, Mi, Fa, Sol, La to the degrees of a hexachord scale. These syllables, later modified to Do, Re, Mi, Fa, Sol, La, Ti, became the solfège system still used in musical education worldwide. Guido's notation system made it possible, for the first time in human history, to transmit music precisely across time and distance: a chant written in one monastery could be sung accurately in another without the intermediary of direct oral transmission. This had revolutionary consequences. Composers could now work with growing confidence in forms of controlled complexity — multiple simultaneous voices in polyphony — that had existed as improvised organum since at least the ninth century but were hard to fix and coordinate through oral transmission alone. The period following Guido saw the development of polyphony, the gradual elaboration of rhythmic notation to complement the pitch notation already established, and the emergence of a distinctly Western musical tradition whose structural innovations would accelerate through the Renaissance and Baroque periods and shape every subsequent development in the music of the world. The medieval period also saw the development of polyphony in the Notre Dame school of the twelfth and thirteenth centuries — composers such as Léonin and Pérotin, working at the Cathedral of Notre Dame in Paris, created organum: elaborate multi-voice elaborations of plainsong melodies in which new voices were added above the original chant, moving in measured rhythmic patterns against the slowly unfolding tenor. These Notre Dame compositions represent the first large-scale experiments in rhythmic notation and in the compositional management of multiple simultaneous melodic lines, and they established the technical foundation on which Renaissance polyphony would build. The journey from bone flute to Bach's Well-Tempered Clavier encompasses approximately 50,000 years of human musical activity; the portion we can document with scores and theory treatises covers only the last millennium. What that documented portion reveals is a tradition of accelerating structural invention in which each generation inherited a set of problems and solutions from the previous generation and produced new ones for the next.