46 HABIT AND INTELLIGENCE. [cHAP. rv. 



cannot safely assert that any properties necessarily belong 

 to matter (other than position in space and mobility) 

 except active and passive dynamical ones ; that is to say, 

 except the power of acting by its forces on other matter, 

 and of being acted on in return. We thus know matter 

 only as a function of force, just as we know force only as 

 a function of matter. 



