COSMIC PHILOSOPHY 



or absence of the given antecedent. Unfortu- 

 nately in the operations of nature these requi- 

 sites are seldom fulfilled : so that the method 

 of difference " is more particularly a method of 

 artificial experiment ; while that of agreement 

 is more especially" the resource employed where 

 experimentation is impossible." 



Now in astronomy we can employ only sim- 

 ple observation. The magnitude and the inac- 

 cessibility of the phenomena render it impossi- 

 ble for us to vary the circumstances, so that 

 experiment is out of the question. Neverthe- 

 less here the phenomena are so simple that 

 the method of agreement alone carries us far 

 toward certainty ; and accordingly in astronomy 

 the art of observation has been brought to such 

 a pitch of perfection, and the conditions of an 

 accurate observation are so thoroughly under- 

 stood, that it is here that the use of this imple- 

 ment of induction must be studied. 



In physics, both molar and molecular, and 

 in chemistry, the phenomena become far more 

 complicated. Yet here we become able to vary 

 the phenomena almost indefinitely ; and accord- 

 ingly physics and chemistry are the inductive 

 sciences par excellence^ in which experiment, the 

 great engine of induction, is employed most suc- 

 cessfully, and in which, therefore, is especially 

 to be studied the proper use of the method of 

 difference. 



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