When I look up at the stars and contemplate the space between each light, I feel a rush of gratitude to be a part—albeit a minuscule part—of such a beautiful and balanced cosmos.
In the Middle Ages, the balance between the planets, things on earth, and the human body was understood as a musical harmony, sometimes referred to as the “Harmony of the Spheres.” Inherited from the ancient Greeks, this was a central concept in medieval music theory that paints revolving planets in a romanticized mathematic allegory of celestial music. One allegorical example is the Myth of Er, a story retold by Socrates in Plato’s Republic about the soul’s journey after death.
The story goes something like this: A warrior by the name of Er, son of Armenius, dies honorably in battle. As his body waits for burial, his soul is transported to the heavens on a pillar of light resembling a rainbow. In heaven, Er witnesses the revolution of all the planets and hears beautiful music coming from them.
The sound is explained as emanating from the motion of the planets, but also the fact that each planet has its own resident Siren (half woman, half bird creature) who sings a unique musical pitch. The three Fates also sing in harmony with the Sirens: Lachesis sings the past, Clotho sings the present, and Atropos sings the future. The harmony made by the combination of the Sirens and the Fates is an allegory for the belief that human destiny was connected to the movements of the stars.
Plato deliberately used mythical allegories as a way to keep his scientific knowledge a “secret.” You could either just listen to the nice story, or you could think really hard about it and unpack all the numerical references to understand the mathematical calculations.

a string instrument
Because of the distances between the planets, plus the direction and speed of their orbit, mathematicians like Pythagoras calculated the ratios of these pitches which corresponds to the harmonic ratios found in musical intervals. The most significant of these intervals include the perfect 5th (3:2), the perfect 4th (4:3), and the octave (2:1).
String instruments are especially useful for visualizing and hearing these intervals. For example, if you press down on the middle of a string with your finger, you are “dividing” it in half to get the ratio 2:1. The resulting pitch is an octave higher than that of the open string. For the medieval music theorist, the string instruments in this scenario are a microcosm that reflects the macrocosm that is the universe.
Furthermore, the medieval imagination saw these ratios and numbers in many aspects of the natural world beyond the planets and strings. The human body also contains these ratios and the right kind of music was thought to be able to influence the emotions and even behavior.

A popular myth of Pythagoras that circulated widely in medieval music treatises tells of how he was able to calm a drunken youth who was accosting a woman by playing the correct melody on his instrument.
Plato, and other Pythagoreans, believed that Pythagoras could hear the harmony of the spheres through contemplation of the heavens, even though he was here on earth. Today, we know that in the vacuum of space sound waves cannot exist because they need a substance like air or water to travel through.
However, NASA has recorded radio emissions from celestial bodies such as the sun and other planets. When these radio waves are converted into sound waves, you can hear music-like qualities. (The sun is a C#, but the other planets have varied sound contours). Listen here for the sounds:
https://www.nasa.gov/vision/universe/features/halloween_sounds.html
Some music theorists in the Middle Ages argued that the planets did indeed make sound because of their motion. Others thought that literal heavenly music was preposterous (thanks, Aristotle). However, the idea of harmonic ratios as window into the cosmos carried significant cultural impact for music, astrology-astronomy, and travel. I will give you two musical-poetic examples from the troubadours that involve travel, and the notion of luck or fortune coming from the stars.
The ability to navigate while traveling is essential for arriving safely at your destination. Thanks to GPS, today we barely have to think about how to get to where we’re going. Before satellites however, people navigated by the stars. Sailors are particularly well-known for needing this skill, since there are no “landmarks” to orient your position when you are out at sea. Stars were also important astrological symbols that foretold good or back luck.
The following song by the troubadour Peire Vidal, Atressi co.l perilhans, uses imagery of sailing to describe his love life. In the first stanza, he is unlucky in love like a ship-wrecked sailor who has no guiding star. Then his luck changes and his “star” (i.e. beloved) comes to his rescue.
Atressi co・l perilhans I am just like a ship-wrecked man, Que sus en l’aigua balansa, Tossed in the water Que non a conort de vida, With no hope of survival, Tan suefre greu escharida Suffering such evil fortune Que paor li toll membransa, That fear robs him of his senses, E pueis quan ven a bon port Until finally he arrives safely in port, Per aster o per secors: Rescued or guided by a star: Tot aitals astres m’a sors Such a star has come to my aid Per qu’ieu ai assez razo And has given me good reason De far novella chanso. To compose a new song. Fis amics sui benanans I am the well-loved true friend Et ai per dreg benenansa And rightly I am favored; Tan bon’aventura∙m guida, Such good fortune guides me, Que lieis qu’a valor complida For she who is the most worthy M’a mese m bon’esperansa, Has given me good hope, E m’a trait de mala sort, And has plucked me from my evil destiny, Si que∙l neus me sembla flors So that to me the snow resembles flowers E∙l glatz jardis e verdors, And the ice a verdant garden. Et ai fag per dreg mon pro I have justly gained my advantage Tant quez enrequitz en so. And am enriched by it.
You can find the complete song in Veronica M. Fraser’s book The Songs of Peire Vidal (pp. 102-105). Unfortunately, no melody survives for this song. But a similar theme can be found in a song by Guiraut Riquier, Pus astres no m’es donatz, which survives with both words and melody. In this song, Guiraut complains that his star has not granted him good fortune in love, so he has decided to go to Catalonia (Spain) where the people know all about courtly love and how to appreciate troubadours properly.
You can listen to the song on YouTube here, or if you want to learn to play and sing it yourself, you can download the my transcription of the sheet music below.
You can find an English translation in the book, Songs of the Troubadours and Trouvères: An Anthology of Poems and Melodies by Samuel N. Rosen, Margaret Switten, and Gerard Le Vot (page 175):