22 THE DOCTRINE OF DESCENT. 



aversion in the higher consciousness of man and of the 

 superior animals, till we see all reaction to external ex- 

 citation dwindle into the scarce perceptible motions of 

 the simplest protoplasmic animalculae, it is evident that 

 there can be no question here of either consciousness 

 or will. We cannot then separate the idea of those 

 sensations of desire and aversion, by which mo- 

 tions are excited, from the elementary attributes of 

 matter, as we are wont to do with regard to the 

 higher animals. 6 



In precisely the same sense, it was said some years 

 ago by one of the most talented investigators of lan- 

 guage Lazarus Geiger, now unfortunately deceased : 6 

 " But how is it, if further down, below the world of 

 nerves, a sensation should exist which we are not capa- 

 ble of understanding? And it probably must be so. 

 For as a body that we feel could not exist unless it 

 consisted of atoms that we do not feel, and as we could 

 not see a motion were it not accompanied by waves 

 of light which we do not see, neither could a complex 

 living being experience a sensation strong enough for 

 us to feel it also, in consequence of the motion by 

 which it is manifested, if something similar, though far 

 weaker and imperceptible to us, did not occur in the 

 elements, that is to say, in the atoms. If we only con- 

 sider that we are as little capable of knowing that the 

 falling stone feels nothing, as that it does feel ; it is 

 fully open to us to decide, in accordance with the 

 greatest probability, that the world is susceptible of 

 explanation." 



We have examined the limits which the investigation 

 of nature has prescribed for itself. The organic world, 



