468 ON THE ORIGIN OF FORCE. 



this one and only agent which matter obeys in its changes 

 of form and situation. We may hesitate about admitting 

 into the system of created things around us so vast an 

 amount of additional or extraneous vis viva, as the total- 

 ity of animal exertion since the first introduction of life 

 upon earth would seem to imply. But this is not neces- 

 sary. The actual 7^;r^ necessary to be originated io give 

 rise to the utmost imaginable exertion of animal power 

 in any case, may be no greater than is required to re- 

 move a single material molecule from its place through 

 a space inconceivably minute no more in comparison 

 with the dynamical force disengaged, directly or indirectly, 

 by the act, than the pull of a hair trigger in comparison 

 with the force of the mine which it explodes. But without 

 the power to make some material disposition, to originate 

 so?ne movement, or to change, at least temporarily, the 

 amount of dynamical force appropriate to some one or 

 more material molecules, the mechanical results of 

 human or animal volition are inconceivable. It matters 

 not that we are ignorant of the mode in wliich this is 

 performed. It suffices to bring the origination of dyna- 

 mical power, to however small an extent, within the 

 domain of acknowledged personality. 



(lo.) It will perhaps be objected to this, that the prin- 

 ciple so generally cited, and now so universally recog- 

 nized as a dominant one in physics that of the "con- 

 servation of force " stands opposed to any, even the 

 smallest amount of arbitrary change in the total of 

 *' force " existing in the universe. This principle, so far 

 as it rests upon any scientific basis as a legitimate conclu- 



