From my understanding, It's trying to discuss how music gracefully combines things that normally will not go together (opposites) by having similar things amplified (unification of the multiples) and the opposites working together/complementing each other (agreement of opposites).

Basically the harmony aspect puts together stuff that not only is alike but also things that in the normal world may not work together. My example would be a soft voice with hard music. When looking professional speechs, that never works, but with music, there can be some way that works beautifully.

Good luck with the paper. Just break it down as much as you can and provide examples and I am sure you can do it!

Oh Thank you so much. Your explanation help me a lot.