PROFESSOR VIRCHOW AND EVOLUTION 429 



presentable. But we can form no picture of the process 

 whereby consciousness emerges, either as a necessary link, 

 or as an accidental by-product, of this series of actions. 

 The reverse process of the production of motion by con- 

 sciousness is equally unpresentable to the mind. We are 

 here in fact on the boundary line of the intellect, where 

 the ordinary canons of science fail to extricate us. If we 

 are true to these canons, we must deny to subjective phe- 

 nomena all influence on physical processes. The me- 

 chanical philosopher, as such, will never place a state of 

 consciousness and a group of molecules in the relation 

 of mover and moved. Observation proves them to inter- 

 act; but, in passing from the one to the other, we meet 

 a blank which the logic of deduction is unable to fill. 

 This, the reader will remember, is the conclusion at which 

 I had arrived more than twenty years ago. I lay bare 

 unsparingly the central difficulty of the materialist, and 

 tell him that the facts of observation which he considers 

 so simple are " almost as difficult to be seized mentally 

 as the idea of a soul.'* I go further, and say, in effect, to 

 those who wish to retain this idea, "If you abandon the 

 interpretations of grosser minds, who image the soul as 

 a Psyche which could be thrown out of the window an 

 entity which is usually occupied, we know not how, among 

 the molecules of the brain, but which on due occasion, 

 such as the intrusion of a bullet or the blow of a club, can 

 fly away into other regions of space if, abandoning this 

 heathen notion, you consent to approach the subject in 

 the only way in which approach is possible if you con- 

 sent to make your soul a poetic rendering of a phenome- 

 non which, as I have taken more pains than anybody else 

 to show you, refuses the yoke of ordinary physical laws 



