there's a striking similarity in these two passages:
“For the word ‘nature’ is applied to what is according to nature and the natural in the same way as ‘art’ is applied to what is artistic or a work of art. We should not say in the latter case that there is anything artistic about a thing, if it is a bed only potentially, not yet having the form of a bed; nor should we call it a work of art. The same is true of natural compounds. What is potentially flesh or bone has not yet its own ‘nature,’ and does not exist ‘by nature,’ until it receives the form specified in the definition, which we name in defining what flesh or bone is.”
“The term ‘musical’ is used by the Germans in a sense foreign to that in which any other language employs it... ‘Musical’ is derived from ‘music’, like ‘poetical’ from poetry, or ‘physical’ from physic(s). When I say, ‘Schubert was one of the most musical among men,’ it is the same as if I should say, ‘Helmholtz was one of the most physical among men.’ That is musical, which sounds in rhythms and intervals. A cupboard can be ‘musical’ if ‘music-works’ be enclosed in it.”
on one hand Busoni is pointing out the absurdity of the term musical as applied to individuals, given that unless they are singers (he mentions in a footnote) they themselves do not produce musical sounds. a cupboard (music box, I thinkdoes, or an instrument, even if manipulated by people. on the other hand, he consistently saw and described in his treatise music as a living spirit, and a being unto itself. at the end of this chapter he adds a characteristically 'artistic' coda:
“A thousand hands support the buoyant child and solicitously attend its footsteps, that it may not soar aloft where there might be risk of a serious fall. But it is still so young, and is eternal; the day of its freedom will come. - When it shall cease to be ‘musical.’”