ON THE ORIGIN OF FORCE. 467 



direction^ and impinging upon tlie material atoms of 

 bodies ; as a mode of accounting for gravitation, is too 

 grotesque to need serious consideration ; and besides, will 

 render no account of the phenomenon of elasticity. Be- 

 sides this, I am not aware of any other attempt to embody 

 in a tangible form the notion of a substitute for the con- 

 ception of dynamical force arising out of the elementary 

 conceptions of motion and inertia. There is a tendency 

 indeed, of late apparent, to attribute tlie elastic pressure 

 of a gas on its containing envelope, as due to the collisive 

 shock of its particles conceived as existing in a continual 

 state of vibration, or of circulation round each other. 

 Eut the maintenance of such vibrations or revolutions in- 

 volves the supposition of inter-molecular coercive forces, 

 and is not, therefore, to be classed with such attempts. 



(9.) If it be true, then, that the conception of force 

 as the originator of motion in matter without bodily con- 

 tact, or the intervention of any intermedmm, is essential 

 to a right interpretation of physical pha^nomena ; and if 

 it be equally so, on the other hand, that its exertion 

 makes itself manifest to our personal consciousness by 

 that peculiar sensation of effort which is not without its 

 analogue in purely intellectual acts of the mind; it comes, 

 not unnaturally, to be regarded as affording a point of 

 contact, a connecting link between these two great de- 

 partments of being between mind and matter the one 

 as its originator, the other as its recipient. The control 

 we possess over the external world we are sure must 

 arise from a capacity somehow inherent in the intellec- 

 tual part of our nature, to originate or call into action 



