H THE PROGEESS OF SCIENCE 95 



Hence, as the phenomena exhibited by living 

 beings, in so far as they are material, are all molar 

 or molecular motions, these are included under 

 the general law. A living body is a machine by 

 which energy is transformed in the same sense as 

 a steam-engine is so, and all its movements, molar 

 and molecular, are to be accounted for by the 

 energy which is supplied to it. The phenomena 

 of consciousness which arise, along with certain 

 transformations of energy, cannot be interpolated 

 in the series of these transformations, inasmuch as 

 they are not motions to which the doctrine of the 

 conservation of energy applies. And, for the same 

 reason, they do not necessitate the using up of 

 energy ; a sensation has no mass and cannot be 

 conceived to be susceptible of movement. That a 

 particular molecular motion does give rise to a 

 state of consciousness is experimentally certain ; 

 but the how and why of the process are just as 

 inexplicable as in the case of the communication 

 of kinetic energy by impact. 



When dealing with the doctrine of the ultimate 

 constitution of matter, we found a certain resem- 

 blance between the oldest speculations and the 

 newest doctrines of physical philosophers. But 

 there is no such resemblance between the ancient 

 and modern views of motion and its causes, except 

 in so far as the conception of attractive and repul- 

 sive forces may be regarded as the modified 

 descendant of the Aristotelian conception of forms. 



