434 Molecular Motion. [October, 



its determination, is absolute, it must hold equally true in 

 the mental world as in the physical. For example, it is 

 just as impossible to conceive the will being determined by 

 an act, as to conceive the motion of the cannon-ball being 

 determined by the explosion of the powder. It is difficult 

 to say whether in physics or in metaphysics the distinction 

 is of most importance. 



What is the cause of determination ? What is that 

 something which determines the energies of the universe 

 and guides the motion of the material particles ? This is 

 the all-important question, whether as regards life-theories, 

 theism, or evolution. 



To a large extent the discussions and diversity of opinion 

 which at present prevail in reference to the mystery of life 

 and the distinction between the organic and the inorganic 

 world take their rise from confusion of ideas regarding the 

 difference between the cause of motion and the cause of the 

 determination of motion. The various theories may be 

 divided into two classes, — the advocates of the one class 

 maintaining that all the phenomena of life, all the changes 

 which take place in organic nature, are the result of purely 

 chemical and physical agencies ; while the other party 

 maintain that there must be something more than the ordi- 

 nary chemical and physical forces at work — in short, that 

 life and organic nature imply the action of a force altogether 

 different from those which belong to the domain of chemistry 

 and physics, and to which the name of " vital force " has 

 been applied. 



Evidently the vital energies of the plant and animal are 

 derived from the chemical affinities of the food and nutri- 

 ment which they receive. Vital force is chemical force 

 transformed. The same remark holds true of the mecha- 

 nical and other physical energies of the body. The energy 

 by which the arm is raised or by which the heart beats 

 is derived from the food. Animal heat is derived from 

 chemical combination. 



So far as all this is concerned, the advocates of the 

 physical theory of life are evidently correct:. But are they 

 warranted in affirming, as they do, that all the energies 

 of plants and animals are either chemical or physical ? 

 Whether such an affirmation be correct depends entirely on 

 the idea which may be attached to the terms chemical and 

 physical. 



When the advocates of the physical theory of life affirm 

 that every energy in organic nature is either chemical or 

 physical, they certainly do not mean to include under the 



