ON THE PHYSICAL BASIS OF LIFE 111 



be well founded. While, on the contrary, could David 

 Hume be consulted, I think he would smile at their perplex- 

 ities, and chide them for doing even as the heathen, and 

 falling down in terror before the hideous idols their own 

 hands have raised. 



For, after all, what do we know of this terrible "matter," 

 except as a name for the unknown and hypothetical cause 

 of states of our own consciousness ? And what do we know 

 of that "spirit" over whose threatened extinction by matter 

 a great lamentation is arising, like that which was heard at 

 the death of Pan, except that it is also a name for an unknown 

 and hypothetical cause, or condition, of states of conscious- 

 ness ? In other words, matter and spirit are but names for 

 the imaginary substrata of groups of natural phenomena. 



And what is the dire necessity and "iron" law under 

 which men groan? Truly, most gratuitously invented 

 bugbears. I suppose if there be an "iron" law, it is that of 

 gravitation; and if there be a physical necessity, it is that a 

 stone, unsupported, must fall to the ground. But what is 

 all we really know, and can know, about the latter phe- 

 nomena ? Simply, that, in all human experience, stones have 

 fallen to the ground under these conditions; that we have 

 not the smallest reason for believing that any stone so cir- 

 cumstanced will not fall to the ground; and that we have, on 

 the contrary, every reason to believe that it will so fall. It 

 is very convenient to indicate that all the conditions of belief 

 have been fulfilled in this case, by calling the statement that 

 unsupported stones will fall to the ground, "a law of Nature." 

 But when, as commonly happens, we change will into must, 

 we introduce an idea of necessity which most assuredly does 

 not lie in the observed facts, and has no warranty that I can 

 discover elsewhere. For my part, I utterly repudiate and 

 anathematise the intruder. Fact I know; and Law I know; 



