Concerning the Ten Commandments, which are the Heads of the Law (33)

but as it seems to me, he at that time wrought a most conspicuous and evidently holy miracle, commanding an invisible sound to be created in the air, more marvellous than all the instruments that ever existed, attuned to perfect harmonies; and that not an inanimate one, nor yet, on the other hand, one that at all resembled any nature composed of soul and body; but rather it was a rational soul filled with clearness and distinctness, which fashioned the air and stretched it out and changed it into a kind of flaming fire, and so sounded forth so loud and articulate a voice like a breath passing through a trumpet, so that those who were at a great distance appeared to hear equally with those who were nearest to it.