Early Greek philosophers were highly imaginative in describing what the universe was made of. One said water, another fire, another, earth, etc. Their models had little to do with observation. Once the imaginative picture was formed, only then, it seems, did any rational thought kick in, to build up a detailed picure. Pythagoras was perhaps the first significant philosopher to combine his imagination with observation and rational thought to develop his mathematical, musical model of the universe. Plato shone the bright light of reasoned argument on this universe and the rest is history.
With regard to music, Pythagoras identified three types, described by the academics of the Middle Ages as musica mundana, the macrocosmic music of the spheres, musica humana, the microcosmic music contained by the human being and the lowest form of music, musica instrumentalis, the ordinary music made by musicians.
A distinction was commonly made between mere musical performers, cantores, and those considered to be the true artists, who theorised about music and its relationship with the cosmos, the musici.
To explore the spirit of music, I'm inclined to spend less time on musica instrumentalis as this is the body of music whose bones have been picked clean by endless books and articles about music. It's the microcosmic and macrocosmic aspects that could be fruitful as they made up so much of the sum total of music's history and have largely been forgotten. Much of what has been said on this subject appears to be quaint, irrational, plain wrong and consequently thought to be irrelevant. I'm tending to move towards considering them in the light of a psychological understanding of the "imagination", not as fantasy but as a means of perception, a sort of eye on the inner workings of the human condition. For example, cultural myths, all born of human imagination, are a route to understanding the fundamentals of human behaviour.
More on this later, but first, I need more appealing terminology than the old Latin terms, to distinguish our three musical areas of investigation. How about Mind Music, for what goes on in and comes out of the musical brain; Spirit Music, for its universal, philosophical principles; Body Music for the sounds made and heard from instruments, musicians, performances. I'll work with those for a while, see how they develop and if any better terminology emerges. At least this suits the modern holistic idiom, Mind, Body, Spirit.