( 59 2 ?3 



to a noise, and the stellar radiance to a whisper drowned 

 by the noise. What is the nature of the particles which 

 shed this light ? On points of controversy I will not 

 here enter, but I may say that De la Rive ascribes the 

 haze of the Alps in fine weather to floating organic 

 germs. Now the possible existence of germs in such 

 profusion has been held up as an absurdity. It has 

 been affirmed that they would darken the air, and on 

 the assumed impossibility of their existence in the 

 requisite numbers, without invasion of the solar light, a 

 powerful argument has been based by believers in spon- 

 taneous generation. 



Similar arguments have been used by the opponents 

 of the germ theory of epidemic disease, and both par- 

 ties have triumphantly challenged an appeal to the 

 microscope and the chemist's balance to decide the ques- 

 tion. Without committing myself in the least to De la 

 Rive's notion, without offering any objection here to 

 the doctrine of spontaneous generation, without ex- 

 pressing any adherence to the germ theory of disease, I 

 would simply draw attention to the fact that in the at- 

 mosphere we have particles which defy both the micro- 

 scope and the balance, which do not darken the air, and 

 which exist, nevertheless, in multitudes sufficient to re- 

 duce to insignificance the Israelitish hyperbole regard- 

 ing the sands upon the seashore. 



The varying judgments of men on these and other 

 questions may perhaps be, to some extent, accounted for 

 by that doctrine of relativity which plays so important 

 a part in philosophy. This doctrine affirms that the im- 

 pressions made upon us by any circumstance, or combi- 

 nation of circumstances, depends upon our previous 

 state. Two travelers upon the same peak, the one hay- 



