220 Charles Darwin. 



A savage hears the voice of his fellow-man, he 

 hears the voice of the beast, and of the bird ; he 

 also hears the noise of the thunder, and he supposes 

 that the noise is a voice. In these cases he discerns 

 noises, but he does not discriminate one noise from 

 the other, and supposes them all to be voices, and 

 that the noise of the thunder is the voice of the 

 Thunder Bird. To understand facts we must not 

 only discern, but discriminate. 



The next step in the progress of science is classifi- 

 cation. Having discerned and discriminated facts, 

 they must be classified — all those of like nature 

 thrown together. All noises made by living beings 

 for conveying intelligence may be grouped into one 

 class and called voices ; all noises made by explosions 

 grouped in another class ; and so, as we go on dis- 

 cerning, discriminating, and classifying, we collect 

 the materials of philosophy. 



But this is not all of philosophy. Facts have 

 genetic relations. If one thing is done something 

 else will follow, and the highest function of scientific 

 philosophy is to discover the order of succession of 

 phenomena — how phenomena follow phenomena in 

 endless procession, how every fact has had its ante- 

 cedent fact, and every fact must have its consequent 

 fact. This part of science is called evolution, and by 

 this expression scientific men mean to be understood 

 that phenomena go on in endless consequences, and 

 that every act has been preceded by some other act, 

 and that every act will be followed by some other 

 act ; that the causes of all of the phenomena of the 

 universe that we wish to explain in a system of phil- 



