CHAPTER I 



THE RELATIVITY OF KNOW- 

 LEDGE 1 



WHEN we contemplate any portion 

 of matter, such as a cubical block of 

 metal or wood, it appears to our 

 senses to be perfectly solid. No breach of con- 

 tinuity appearing anywhere among the aggregate 

 of visual and tactual perceptions which its pre- 

 sence awakens in us, we are unable to restrain 

 ourselves from imagining that its parts are 

 everywhere in actual contact with each other. 

 Nevertheless, a brief analysis of this opinion 

 will suffice to show that it cannot be maintained 

 without landing us in manifest absurdity. We 

 need only recollect that every portion of matter 

 is compressible, — may be made to occupy less 

 space than before, — and that compressibility, 

 implying the closer approach of the constituent 

 particles of the body, is utterly out of the ques- 

 tion, unless empty space exists between these 

 particles. We are therefore obliged to admit 

 that the molecules of which perceptible matter 

 1 [See Introduction, § 8.] 

 3 



