The Limits of Physical Science. 35 



dowed are, on the hypothesis of evolution, defective 

 in their adaptation to any purpose except the prac- 

 tical end of adjustment to environment, and so to the 

 maintenance of man's life on the earth. Admirably 

 fitted to serve the purpose for which they have been 

 evolved, they fail us when applied to any other use. 

 They cannot, therefore, be depended on as instruments 

 of exact knowledge. The power of sight, for example, 

 is extremely restricted in its compass. Our perception 

 of colour is limited to a narrow range, and within that 

 range is very imperfect. The lower animals are in 

 many instances endowed with more perfect organs 

 than man. Defective sense-perception is corrected by 

 comparison, but even then the means are not furnished 

 for attaining absolute precision. " The mind of man, 

 as Francis Bacon said, is like an uneven mirror, and 

 does not reflect the events of nature without distor- 

 tion."* The most skilful observer cannot adjust his 

 intellectual compensations with perfect success to de- 

 fects of nerve and organ. The gift of exact observa- 

 tion is extremely rare. We tend to see that for which 

 we look. "It is exceedingly rare," says Professor 

 Jevons, " to find persons who can, with perfect fair- 

 ness, estimate and register facts for and against their 

 own peculiar views and theories."-)- The mind brings 

 with it an anticipation which colours the event. Those 

 parts of the concrete whole which favour the conclu- 



* Jevon's Principles of Science, Vol. II., Book IV., Chap. XVIIL 

 t Ibid. 



