A key idea from the time of Pythagoras on was making a differentiation between musica mundana, the cosmic music of the spheres; musica humana, the music contained within every human form, sounding continuously and unheard; and musica instrumentalis, the ordinary music made by musicians. Although Pythagoras had made these distinctions, this is the terminology used in the Middle Ages.
The last of these three was by far of least importance and held in much lower esteem than the study of the first two.
In the Middle Ages almost every learned text about music made a clear distinction between the musici, the theorists who were music's true artists and the cantores, who were mere performers of music.
Music of the Spheres
An idea that prevailed from Pythagoras in classical Greece well into the Middle Ages was that the rules that governed the physics of music also described how the cosmos works.
The planets were conceived as inhabiting cystaline nested spheres with the earth at their centre and the distant stars and constellations at the outer perimeter. Each planet emitted a note caused by its movement through space and acting together the heavenly bodies created a great cosmic harmony.
This outer universe, the macrocosm, was believed to be reflected on earth as the inner man, the microcosm and particularly in alchemy and astrology - as well as music - scholars strove to discover the relationships between the two and thus discover the means to put them in harmony.
An example of the music of the spheres is found in the work of Johannes Kepler whose laws of planetary motion were inspired and informed by music's harmonic series, and the maths of sound and vibrating waves.
Cicero and Scipio
The most widely read description of the Music of the Spheres is contained in a work of fiction by Marcus Tullius Cicero, a Roman philosopher, orator and political theorist, born in 106 BC and assassinated in 43 BC.
In Scipio's Dream, the guide through our universe is Scipio Africanus, hero of the Punic Wars and a great defender of Roman freedom. He leads his grandson, the dreamer, Scipio Africanus the Younger, on a journey among the spheres and into the afterlife. The dreamer asks, "What is that great and pleasing sound that fills my ears?" His grandfather replies, "That is a concord of tones separated by unequal but nevertheless carefully proportioned intervals, caused by the rapid motion of the spheres themselves."