When I had recovered myself from the astonishment occasioned by such a wonderful prospect, I thus addressed Africanus: Pray what is this sound that strikes my ears in so loud and agreeable a manner?
To which he replied: It is that which is called the _music of the spheres_, being produced by their motion and impulse; and being formed by unequal intervals, but such as are divided according to the justest proportion, it produces, by duly tempering acute with grave sounds, various concerts of harmony.

For it is impossible that motions so great should be performed without any noise; and it is agreeable to nature that the extremes on one side should produce sharp, and on the other flat sounds.

For which reason the sphere of the fixed stars, being the highest, and being carried with a more rapid velocity, moves with a shrill and acute sound; whereas that of the moon, being the lowest, moves with a very flat one.

As to the earth, which makes the ninth sphere, it remains immovably fixed in the middle or lowest part of the universe.

But those eight revolving circles, in which both Mercury and Venus are moved with the same celerity, give out sounds that are divided by seven distinct intervals, which is generally the regulating number of all things.
This celestial harmony has been imitated by learned musicians both on stringed instruments and with the voice, whereby they have opened to themselves a way to return to the celestial regions, as have likewise many others who have employed their sublime genius while on earth in cultivating the divine sciences.
By the amazing noise of this sound the ears of mankind have been in some degree deafened; and indeed hearing is the dullest of all the human senses.