Since ancient times music has been understood as number made audible.
Music brings to the sense of hearing the numerical order of nature.
The mind recognises in the beauty of harmonies this order of nature, which is also a pattern in the soul. In music we hear the qualities of the numbers, not simply their quantities, and it is these qualities that move the heart. There is a correlation between the nature of the soul and the nature of the world, and the harmonies of music derive from this correlation, and when we hear music that springs from this nature it tempers the mind and brings it to its natural order and rest. This is why music can restore the mind and heart. Since harmonies are relationships of numbers, and since beauty shines most clearly in what is unified and whole, the most simple, unified and whole numbers produce harmonies, while complex numbers produce discords.