234 PRINCIPLES OF PHYSIOLOGY 



again runs over these curves, the sound 

 must be reproduced. Nature knows nothing 

 of letters and syllables ; words are either 

 simple phones or combinations of phones, 

 and each phone is formed of vibrations. This 

 is nature's longhand method of recording 

 speech : written or printed letters and sylla- 

 bles are a species of shorthand invented by 

 man. 



