ULTIMATE SCIENTIFIC IDEAS. 53 



to conceive the infinite divisibility of matter, is mentally 

 to follow out the divisions to infinity; and to do this would 

 require infinite time. On the other hand, to assert that mat- 

 ter is not infinitely divisible, is to assert that it is reducible 

 to parts which no conceivable power can divide; and this 

 verbal supposition can no more be represented in thought 

 than the other. For each of such ultimate parts, did they 

 exist, must have an under and an upper surface, a right and 

 a left side, like any larger fragment. Now it is impossible 

 to imagine its sides so near that no plane of section can be 

 conceived between them; and however great be the as- 

 sumed force of cohesion, it is impossible to shut out the 

 idea of a greater force capable of overcoming it. So that 

 to human intelligence the one hypothesis is no more accept- 

 able than the other; and yet the conclusion that one or 

 other must agree with the fact, seems to human intelligence 

 unavoidable. 



Again, leaving this insoluble question, let us ask 

 whether substance has, in reality, anything like that extend- 

 ed solidity which it presents to our consciousness. The por- 

 tion of space occupied by a piece of metal, seems to eyes and 

 fingers perfectly filled: we perceive a homogeneous, resist- 

 ing mass, without any breach of continuity. Shall we then 

 say that Matter is as actually solid as it appears? Shall we 

 say that whether it consists of an infinitely divisible element 

 or of ultimate units incapable of further division, its parts 

 are everywhere in actual contact? To assert as much en- 

 tangles us in insuperable difficulties. Were Matter thus 

 absolutely solid, it would be, what it is not — absolutely in- 

 compressible; since compressibility, implying the nearer ap- 

 proach of constituent parts, is not thinkable unless there is 

 unoccupied space between the parts. Nor is this all. It is 

 an established mechanical truth, that if a bodv, moving; at 

 a given velocity, strikes an equal body at rest in such wise 

 that the two move on together, their joint velocity will be 

 but half that of the striking body. Now it is a law of 



