36 The Evolution Hypothesis. 



sion we wish to establish stand clearly out in view, 

 while that which conflicts with the desired conclusion 

 falls into the background. According to the common 

 adage, "seeing is believing;" but it as often happens 

 that "believing is seeing." What man is there, glow- 

 ing and ardent in the pursuit of knowledge, and at 

 the same time altogether unprejudiced and impartial, 

 having no favourite view to support, nor any obnoxious 

 opinion to impugn ? What observer possesses an eye 

 and mind perfectly achromatic? Human frailty 

 scarcely warrants the supposition that such an one 

 is to be found. Individual aberrations from exact 

 truth are no doubt counteracted by the multiplication 

 of observations and the ceaseless conflict of opinion. 

 These compensations in the end work a truer balance 

 of doctrine, and bring theories nearer to reality. But 

 approximations to truth, however close the approach 

 may be, are not sufficient when the philosopher is 

 laying foundations on which his theory of all things 

 is to be based. When he undertakes to unify all 

 knowledge to include in one formula the law of all 

 processes throughout the universe during all time, ap- 

 proximations will not serve. We must build on 

 reality the world of thought, if it is to correspond 

 with the world that is. A slight want of precision, 

 of no account when the target is at fifty paces, wilt 

 prove fatal to accuracy of aim when the distance is a 

 thousand yards ; a trifling inaccuracy in measurement, 

 not worth noticing in calculating the dimensions of a 



