Plutarch De animae procreatione in Timaeo 33

[33] Now then consider whether the soul does not roll and turn and manage the heavens and the celestial bodies by means of those harmonious concords and equal motions that are wrought and fermented within her, being herself most wise and most just. And such she became by virtue of harmonical proportions, whose images representing things incorporeal are imprinted into the discernible and visible parts and bodies of the world. But the chief and most predominating power is visibly mixed in the soul, which renders her harmonious and obedient to herself, the other parts unanimously yielding to her as the most supreme and the divinest part of all. For the Sovereign Artificer and Creator finding a strange disorder and erroneous confusion in the motions of the decomposed and unruly soul, which was still at variance with herself, some things he divided and separated, others he brought together and reconciled to a mutual sympathy, making use of harmony and numbers. By virtue of which, the slightest and meanest of insensible substances, even stocks and stones, the rinds of trees, and sometimes even the rennets of beasts, by various mixtures, compositions, and temperatures, may become the charming objects of the sight, or afford most pleasing perfumes and wholesome medicaments for the relief of mankind, or be wrought and hollowed to send forth pleasing musical sounds. And for this reason it was that Zeno of Citium encouraged and persuaded youth to frequent the theatres, there to observe the variety of melodious sounds that proceeded from horns or cornets, wooden hautboys, flutes and reeds, or any other musical instruments to which the contrivance of art had rightly applied the reason of number and proportion. Not that we will here maintain, with the Pythagoreans, that all things resemble number, for that requires a long discourse to prove it. But where mutual society and sympathy arise out of discord and dissimilitude, that the cause of this is moderation and order, produced by the power of harmony and number, was a thing not concealed even from the poets. And these give to what is friendly and kind the epithet evenly fitted; while, on the other side, men of rugged and malicious dispositions they called unevenly tempered, as if enmity and discord were nothing but a sort of a disproportion. For this reason, he who writes Pindar’s elegy gives him this encomium, the poet plainly inferring complacency of humor and the aptitude of a person to fit himself to all tempers to be an excellency aspiring to virtue itself. Which Pindar himself also testifies, saying of Cadmus, that he listened to true music from Apollo himself. ² Nor must we believe that the theologists, who were the most ancient philosophers, ordered the pictures and statues of the Gods to be made with musical instruments in their hands because they thought the Gods no better than pipers or harpers, but to signify that no work was so becoming to the Gods as accord and harmony.

Now then, as it would be absurd and ridiculous for any man to search for sesquiterces, sesquialters, and duples in the neck, or belly, or sides of a lute or harp,—though every one of these must also be allowed their symmetry of length and thickness,—the harmony and proportion of concords being to be sought for in the sound; so it is most probable that the bodies of the stars, the distances of spheres, and the swiftness of the motions and revolutions, have their sundry proportions, as well one to another as to the whole fabric, like instruments of music well set and tuned, though the measure of the quantity be unknown to us. However, we are to imagine that the principal effect and efficacy of these numbers and proportions, which the Supreme Architect made use of, is that same agreement, harmony, and consent of the soul with itself, by means of which she replenished the heavens themselves, when she came to actuate and perform her office there, with so many infinite beauties, and by which she governs the earth by virtue of the several seasons, and other alterations wisely and artificially measured and varied as well for the generation as preservation of all terrestrial productions.