94 THE NATURE OF MUSIC 



fore these three groups of mode-tones are three 

 groups of mode-relations. Both mode and tonality 

 mean tone-relation, and at one time the two terms 

 were synonymous. The evolutionary expansion qf 

 tonality consequent on the development of modern 

 music has changed all this. While tonality compre- 

 hends all that is mode, mode does not comprehend all 

 that is tonality. Definitions will explain. The mode 

 is the sum of relations in one key. Tonality is the 

 sum of relations in all keys. The mode is concerned 

 with the interharmonic relations of one key, tonality 

 with the interharmonic relations of all keys. Thus 

 tonality is a general term and comprehends all that is 

 mode. The evolution of the mode is therefore the 

 first chapter in the evolution of tonality: the three 

 groups of tones and relations are three evolutionary 

 stages of tonality. The first stage culminated in the 

 completion of the foundation-group of seven diatonics, 

 which is the subject still before us. We have symbol- 

 ized and named each of these tones by a syllable, a 

 note in the key of C, and a scale-number. Each is 

 also known by a technical name which is added to the 

 other names in this example. 



Tonic Super- Mediant Sub- Dominant Sub- Subtonic Tonic 

 tonic dominant mediant 



The unity of the mode-idea is exemplified by all 

 these symbols except the notes which fix the pitch or 

 key of mode on C. 



