Sentence:  As the notes attributed to them go together, so the things themselves make harmonious or inharmonious "chords", and as one sounds a certain note in one <WSD>enneachord</WSD>, all the other entities tuned to that note or its octave vibrate sympathetically. 
Meaning of the word marked with <WSD> tags:  A mystical chord or combination of nine entities that characterizes the "music of the spheres".