xii INTRODUCTION. 



posited in points or centres, and each centre acting 

 on the others, when we review the nervous system 

 in its relations with consciousness we pass from the 

 mere mutual relations of such centres, and find both 

 mind acting on matter, and matter acting on mind. 

 Those who deny the evidence of spirit existing inde- 

 pendent of matter point to the permanence of energy 

 in the material world. They argue that the mind 

 is affected by physical stimuli, and that no mental 

 operation takes place without corresponding physi- 

 cal action. They assume that, were consciousness 

 beyond the circle of physical changes, it would re- 

 main unaffected by them, instead of mind acting on 

 body, and body on mind, as is the case ; but if it be 

 within the circle of physical change then, they argue, 

 it is itself physical, or at least we have no right to 

 suppose that it can exist independent of matter. 

 From the dogma that mind cannot exist independ- 

 ent of matter, one can easily see how simple is the 

 passage to some such formula as that mind is an 

 evolution of matter. But to extract a clear mean- 

 ing from such a formula is not so easy : it is the 

 endowing of matter with properties demonstrated in 

 no physical nor chemical laboratory. Thus when 

 in the passage quoted at p. 23, Hackel speaks of 

 spirit as a function of force he uses a form of words 

 which conveys no meaning. Had he said that force 

 is a function of spirit he might have reached a truly 

 " monistic" philosophy and thrown the mind back on 



