 A third topic of ontological discussion at the “higher” level is the nature of the elements of musical works, such as melodies, harmonies, and rhythms, and how they come together to form complex wholes. At present only Roger Scruton (1997: 19–79; 2007) and Stephen Davies (2001: 47–71) have addressed these questions in depth from a philosophical perspective, but they will be important to understanding the very nature of music, if an appeal is made to such “basic musical features” as pitch and rhythm in the definition of music (see  section 1.2,  above).