130 



THE NATURE OF MUSIC 



Such examples of concurrent alternations of rhythmic 

 and harmonic cadence and repose manifest the direct 

 influence of rhythm upon the harmonic structure of 

 melody, while on the other hand the direct influence 

 of harmony upon the rhythmic structure of melody 

 is manifested in the lengthening of the rhythmic 

 periods of alternating cadence and repose from beats 

 to measures. These reciprocal influences of the two 

 elements, now of rhythm on harmony, now of harmony 

 on rhythm, the two always inseparably combined yet 

 acting and reacting each upon the other in obedience 

 to the inherent shaping principle of equilibrium, these 

 are the chief shaping forces in the evolution of the 

 musical phrase and thence of the larger forms of 

 music. I will pause here a moment to point out 

 how harmony may contract and expand the rhythmic 

 form. In contractions secondary eflScient accents 

 appear within the limits of one measure (see below at 

 a)) while in expansions the regnant harmonies may 

 extend indefinitely and cause the rhythmic forms to 

 be either perfectly regular (see b)) or irregular 

 (see c)). 



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