68 BIOLOGY AND PHYSICAL SCIENCES 



are so familiar has been a constant subject 

 of investigation, and we must consider as well 

 as we can what light they have thrown on 

 the particular problem before us. We must, 

 therefore, try to trace the reasoning which, in 

 its successive developments, has guided them. 



When we regard the conception of the 

 visible and tangible universe as it is presented 

 to us by the physical sciences we find that it 

 not only stands the most searching laboratory 

 tests, but that it also stands the tests of 

 practical experience of a very wide kind. The 

 engineer, the manufacturer, the navigator, the 

 soldier, the lawyer, can apparently rely upon 

 it absolutely. But philosophy points out that 

 " if it corresponds to absolute reality it must be 

 consistent with the whole of our experience ; 

 and first and foremost it must be consistent 

 with our own conscious relations to it, which 

 have, after all, been entirely left out in the 

 laboratory and other tests. 



At first it may seem simple enough to say 

 that we are conscious of the physical world. 

 It is there, plainly before us. But then comes 

 the reflection that the appearance can only be 

 transmitted to us through our sense organs 



