XL J MR. DARWIN'S CRITICS. 283 



And as the law of continuity is as much opposed, as is 

 the common sense of mankind, to the notion that all 

 animals are unconscious machines, it may safely be 

 assumed that no sufficient answer ever will be given 

 to them. 



There is every reason to believe that consciousness is a 

 function of nervous matter, when that nervous matter 

 has attained a certain degree of organization, just as we 

 know the other " actions to which the nervous system 

 ministers," such as reflex action and the like, to be. As 

 I have ventured to state my view of the matter else- 

 where, " our thoughts are the expression of molecular 

 changes in that matter of life which is the source of 

 our other vital phenomena." 



Mr. Wallace objects to this statement in the following 

 terms : 



"Not having been able to find any clue in Professor Huxley's 

 writings to the steps by which he passes from those vital phenomena, 

 which consist only, in their last analysis, of movements by particles of 

 matter, to those other phenomena which we term thought, sensation, 

 or consciousness ; but, knowing that so positive an expression of opinion 

 from him will have great weight with many persons, I shall endeavour 

 to show, with as much brevity as is compatible with clearness, that 

 this theory is not only incapable of proof, but is also, as it appears to 

 me, inconsistent with accurate conceptions of molecular physics." 



With all respect for Mr. Wallace, it appears to me that 

 his remarks are entirely beside the question. I really 

 know nothing whatever, and never hope to know any- 

 thing, of the steps by which the passage from molecular 

 movement to states of consciousness is effected ; and I 

 entirely agree with the sense of the passage which he 

 quotes from Professor Tyndall, apparently imagining that 

 it is in opposition to the view I hold. 



All that I have to say is, that, in my belief, conscious- 

 ness and molecular action are capable of being expressed 

 by one another, just as heat and mechanical action are 



