198 THE PHENOMENA OF MOTION 



called mechanical forces, we have recognised in the 

 chemical forces causes of motion and of change in form 

 and structure, without any observable exhaustion of 

 the force by which these phenomena are produced ; 

 but the origin of the continued manifestation of activity 

 remains still the same ; it is the absence of an opposite 

 force (a resistance) capable of neutralizing it or bring- 

 ing it into the state of equilibrium. 



As the manifestations of chemical forces (the mo- 

 mentum of force in a chemical compound) seem to 

 depend on a certain order in which the elementary par- 

 ticles are united together, so experience tells us, that 

 the vital phenomena are inseparable from matter ; that 

 the manifestations of the vital force in a living part are 

 determined by a certain form of that part, and by a 

 certain arrangement of its elementary particles. If we 

 destroy the form, or alter the composition of the organ, 

 all manifestations of vitality disappear. 



There is nothing to prevent us from considering the 

 vital force as a peculiar property, which is possessed 

 by certain material bodies, and becomes sensible when 

 their elementary particles are combined in a certain 

 arrangement or form. 



This supposition takes from the vital phenomena 

 nothing of their wonderful peculiarity ; it may there- 

 fore be considered as a resting point, from which an 

 investigation into these phenomena, and the laws which 

 regulate them, may be commenced ; exactly as we 

 consider the properties and laws of light to be depend- 



