ACCENT AND REGNANT HARMONY 123 



seven diatonics to undergo a change of relation, 

 namely, from 5 to 1. Next to follow was do, chang- 

 ing its relation from 1 to 5. These bond-tones plainly 

 indicate that the roots of the two harmonies which 

 each connects lie sl fifth apart. Thus I — V connected 

 by sol and I — IV connected by do are called fifth- 

 related harmonies. These fifth-related harmonies are 

 not only the first of their kind, but are the first of any 

 kind. This explains why fifth-related harmonies are 

 nearest related harmonies, why fifth-related keys are 

 nearest related keys. These fifth-relations also dis- 

 close the origin of the authentic closing-cadence V — I, 

 of the plagal closing-cadence IV — I and of the fifth- 

 cycle of keys. In these diatonic-Major relations the 

 bond-tones sol and do are in repose and stable, and 

 this is true of all bond-tones of fifth-related harmonies. 

 The case is otherwise with the bond-tones fa and la 

 which in all the relations thus far presented main- 

 tain their unstable character, which is explained by 

 the fact that they belong to the genus dissonance. 

 Whether as bytones to I or as regnant tones in V9 

 and IV or as bond-tones connecting V9 — ^IV and 

 IV — ^V9, both fa and la manifest this unstable char- 

 acter, and they do not gain repose and stability until 

 they appear in Minor as we shall see in the next 

 chapter. Meanwhile I present them as connecting 

 links between V9 and IV. 



