Yeah I ' ve never read a harmony book that I liked more . His philosophical digressions are so great , and he ' s funny too , especially the section on nonharmonic tones . But what I really notice the most is that he takes NOTHING for granted . In a book like say , Piston ' s , it ' s all this is how it is because people do it , and the examples he uses are too convoluted to be useful when learning . But Schoenberg seems so intent on explaining the logic behind EVERYTHING , and they all seem to be very original interpretations . No harmony book had been so inspiring to me in a compositional sense . I think few other theory authors can do that , and help you understand the difference between making exercises and actually writing music . Here ' s the 2 important pages from structural functions that modify his theory of modulation a bit , or better systematize it Regionality in Structural Functions in Harmony