HERMANN VON HELMHOLTZ 



principle. As remarked by Sir John Herschel, 1 ' we 

 must never forget that it is principles, not phenomena 

 laws, not insulated independent facts which are the 

 objects of inquiry to the natural philosopher. As 

 truth is simple, and consistent with itself, a principle 

 may be as completely and as plainly elucidated by the 

 most familiar and simple fact, as by the most imposing 

 and uncommon phenomenon. The colours which 

 glitter on a soap-bubble are the immediate conse- 

 quences of a principle the most important from the 

 variety of phenomena it explains, and the most 

 beautiful, from its simplicity and compenduous neat- 

 ness, in the whole science of optics.' 



1 Discourse on the Study of Natural Philosophy. London, 1830, p. 13. 



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