ORIGIN OF PHYSICAL CONCEPTS 33 



of a constant Force is stated in the formula JMV 2 . 

 To ascertain M, therefore, we must have given F 

 and V, and these are both conceptions the original 

 idea of which is derived from our exertional 

 activity. 



Quantity of Matter originally means the same as 

 amount of resistance to initiation of motion, at first 

 estimated by the varying amount of personal muscular 

 energy required to effect the motion in question, 

 thereafter objectively and scientifically by com- 

 parison with some independent standard whereby 

 a more exact estimation can be attained than was 

 possible by a mere reference to the varying infer- 

 ences of the individual who might exert the 

 force. 



Space, Mass, Force are all therefore ideas which 

 are furnished to us out of our experience as potent 

 actors, and the recognition of this great truth pro- 

 vides us with the means of clearly apprehending and 

 co-relating our conceptions of the external world, 

 the framework of our Knowledge. 



The true distinction between a percept and a 

 concept is just that a percept is a concept associated 

 with the dynamic system discovered in and by 

 our exertional activity. 



In like manner we find here the true solution of 

 the many questions which have been raised as to the 

 3 



