THE SCIENTIFIC MOOD 19 



astray, and, the more strenuously he struggles 

 on, the farther will he find himself from his true 

 goal." 



Many children seem to pass through an inter- 

 esting stage in which they fail to discriminate 

 between their dream-pictures and their wide- 

 awake pictures of actual occurrences, and it was 

 probably ingenuousness rather than any lack of 

 good faith that led some of the old naturalist- 

 travellers, in the glamour of strange lands, to 

 mix up in their diaries what they actually saw 

 and what the natives told them was to be seen. 

 And we do not need to go back to ancient history 

 to find examples. 



The scientific worker is well aware that in 

 measurements and observations the accuracy at- 

 tainable is only approximate, and that the degree 

 of approximation varies with the individual. 

 The personal equation has been for a long time 

 frankly recognized and allowed for in astronomy; 

 it is also sometimes estimated in chemistry and 

 physics; but it must be recognized all round. 

 Science begins with measurement and there are 

 some people who cannot be measurers; and just 

 as we distinguish carpenters who can work to this 

 or that fraction of an inch of accuracy, so we 

 must distinguish ourselves and our acquaint- 

 ances as able to observe and record to this or 

 that degree of truthfulness. 



