138 THE FOUNDATIONS OF ZOOLOGY 



Berkeley as he has in Spencer's realism, or in the materialism of 

 German physics, or in the monism of the psychologists ; but unless 

 he knows what the relation between mind and matter is, he can- 

 not join the throng of worshippers before the shrine of this modern 

 idol of the theatre; for its leader tells him that suspension of judg- 

 ment on this difficult question is as fatal as disbelief. 



Proof that we should not be here if our remote ancestors had 

 not responded to the order of nature as they did is no proof that 

 our minds are a measure of nature, or that our responses will be 

 valuable in the future, or that nature is determinate. 



Now the difference between belief that the ultimate test of 

 truth is the inconceivability of its negative, and belief that our 

 practical test of truth is evidence, is this : that while inability to 

 conceive the negative of a proposition may be absolute to us, as 

 nature has made us, at our present intellectual level, evidence is 

 progressive, and can afford no basis for ultimate philosophy. 



Our pre-Cambrian ancestors may have been unable to conceive 

 the negative of many propositions ; but what does the inability of 

 a turnip or a sponge to conceive the negative of Newton's laws 

 signify } Or what would our own inability signify if we should 

 sometime find out that the ponderable matter which makes up 

 what we call " our universe " has been sifted out or segregated 

 from other forms of matter, by its property of weight t For no 

 less distinguished an authority than Herschel held that there is 

 proof of the existence of levitative matter as well ~ as gravitative 

 matter. 



One volume of Herbert Spencer's " Philosophy " is devoted to 

 proof that we primarily know objects; but to this long argument 

 Berkeley answers : Granted. Most assuredly we primarily know 

 objects ; but he tells us that the objects we know primarily are 

 objects of sense. 



So the frozen river of philosophy grinds on, scratching the 

 surface of the everlasting hills, and melting before the genial sun- 

 shine of science, only to receive new accretions from the unknown 

 and frozen space beyond the snow-line. 



Some fifteen hundred years have passed since we were told 

 by Procles that *' there are two sorts of philosophers. The one 

 placed Body first in the order of beings, and made the faculty of 



