18 INTRODUCTION TO SCIENCE 



currences it is often difficult to give a quite 

 accurate account of what took place. This is 

 partly due to the dash of the artistic mood which 

 most men have. It is often due to the untrained 

 eye, which sees only what it has the power of 

 seeing, sometimes little indeed and, in the 

 opposite direction, to preconceptions which often 

 enable men to see what is not to be seen. It is 

 also due to lack of discipline in the method of 

 science; thus nothing is commoner than a nail* 

 ration that mingles observation with unconscious 

 inferences from observation, which is one of the 

 elementary fallacies. 



"Man, unscientific man," Sir Michael Foster 

 said, "is often content with 'the nearly' and 'the 

 almost.' Nature never is. It is not her way to 

 call the same, two things which differ, though the 

 difference may be measured by less than the 

 thousandth of a milligramme or of a millimetre, 

 or by any other like standard of minuteness. 

 And the man who, carrying the ways of the 

 world into the domain of science, thinks that he 

 may treat Nature's differences in any other way 

 than she treats them herself, will find that she 

 resents his conduct; if he in carelessness or hi 

 disdain overlooks the minute difference which 

 she holds out to him as a signal to guide him 

 in his search, the projecting tip, as it were, 

 of some buried treasure, he is bound to go 



