MATTER, MOTION, AND FORCE 



ascertain the axiom upon which they depend, 

 since here, if anywhere, must be found the pri- 

 mordial truth which we are seeking. 



Since we cognize any portion of matter what- 

 ever only as an aggregate of coexistent posi- 

 tions which offer resistance to our muscular 

 energies ; since it is primarily by virtue of such 

 resistance that we distinguish matter from empty 

 space ; it follows that our idea of matter is built 

 up of experiences of force, and that the inde- 

 structible element in matter is its resisting 

 power, or the force which it exerts. Considering 

 different portions of matter in their relations to 

 each other, we are brought to the same conclu- 

 sion. When we say that it is chemistry which 

 has proved with the balance that no matter is 

 ever annihilated, we imply that the test of the 

 presence of matter is gravitative force, and that 

 this force is proportional to the quantity of 

 matter. 



The case of motion is precisely similar. We 

 cognize motion as the successive occupation of 

 a series of positions by an aggregate of coexist- 

 ent positions which offer resistance ; and the 

 essential element in the cognition — " the ne- 

 cessity which the moving body is under to go 

 on changing its position " — has been proved 

 to result from early experiences of force as mani- 

 fested in the movements of our muscles. Con- 

 sequently, as Mr. Spencer observes, when we 

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