6O THEY MODIFY SOLAR REACTION. 



the extreme thrill of the nerves of feeling recog- 

 nized as pain. The conversion of mechanical 

 action into heat is early learned by the sensation 

 of warmth felt on rubbing the hands forcibly to- 

 gether, long before the knowledge is theoretically 

 acquired. The impression of " seeing stars," pro- 

 duced by a blow on the head, is another exempli- 

 fication of the conversion of mechanical action 

 into light. 



The mechanical action of the orbital planetary 

 force being made manifest by reaction from the sun 

 as sunshine, we must look to this reaction for the 

 immediate source of sensation, and of knowledge 

 .of the world around us. It is narrated in classic 

 story, that " the rising sun excited the morning 

 breezes to thrill the chords of the harp of Mem- 

 non to melodious vibrations." So the exciting 

 power of the rising sun thrills the nerves of every 

 living animal, as the attuned strings of a harp. 

 The vibratory solar reaction is modified by the 

 lily and the rose, so as to reach the eye in varied 

 colors ; it is modified by their exhalations, so as to 

 reach the olfactory nerves as odors ; it is modified 

 by the juices of plants and fruits, so as to reach 

 the nerves of the tongue as flavors. 



A general inattention to the true functions of 

 the sensorial nerves, as tests of physical science, 

 has so blended ideas of mechanical causes and 

 effects as to be still a most serious obstacle in 

 the way of knowledge. Identical mechanical im- 



