THE SECRET OF THE WILLOW WREN 131 



due to the human emotions which they express 

 or seem to express. If the voice simulates that 

 of a maniac, or of a being tortured in body or mind, 

 or overcome with grief, or maddened with terror, 

 the blood-curdHng and other sensations proper 

 to the occasion will be experienced ; only, if we 

 are familiar with the sound or know its cause, the 

 sensation will be weak. Similarly, if in some deep, 

 silent wood we are suddenly startled by a loud 

 human whistle or shouted " Hi ! " although we 

 may know that a bird, somewhere in that waste 

 of foliage around us, uttered the shout, we yet 

 cannot help experiencing the feelings — a combina- 

 tion of curiosity, amusement, and irritation — which 

 we should have if some friend or some human being 

 had hailed us while purposely keeping out of sight. 

 Finally, if the bird- sounds resemble refined, bright, 

 and highly musical human voices, the voices, let 

 us say, of young girls in conversation, expressive 

 of various beautiful qualities — sympathy, tender- 

 ness, innocent mirth, and overflowing gladness 

 of heart — the effect will be in the highest degree 

 delightful. 



Herbert Spencer, in his account of the origin 

 of our love of music in his Psychology, writes : 

 " While the tones of anger and authority are harsh 



