THE ART OF SCIENTIFIC INVESTIGATION 



crystal with the correct configuration, so did the falling apple 

 provide a model for Newton's mind. Sir Henry Souttar has 

 pointed out that it is the content of the observer's brain, 

 accumulated by years of work, that makes possible the moment 

 of triumph. This aspect of chance observation will be discussed 

 further in the chapters on observation and on intuition. 



Anyone with an alertness of mind will encounter during the 

 course of an investigation numerous interesting side issues that 

 might be pursued. It is a physical impossibility to follow up all 

 of these. The majority are not worth following, a few will reward 

 investigation and the occasional one provides the opportunity of 

 a lifetime. How to distinguish the promising clues is the very 

 essence of the art of research. The scientist who has an indepen- 

 dent mind and is able to judge the evidence on its merits rather 

 than in light of prevailing conceptions is the one most likely to 

 be able to realise the potentialities in something really new. He 

 also needs imagination and a good fund of knowledge, to know 

 whether or not his observation is new and to enable him to see 

 the possible implications. In deciding whether a Hne of work 

 should be followed, one should not be put off it merely because 

 the idea has already been thought of by others or even been tried 

 without it leading anywhere. This does not necessarily indicate 

 that it is not good; many of the classic discoveries were 

 anticipated in this way but were not properly developed until 

 the right man came along. Edward Jenner was not the first to 

 inoculate people with cowpox to protect them against smallpox, 

 William Harvey was not the first to postulate circulation of the 

 blood, Darwin was by no means the first to suggest evolution, 

 Columbus was not the first European to go to America, Pasteur 

 was not the first to propound the germ theory of disease, 

 Lister was not the first to use carbolic acid as a wound antiseptic. 

 But these men were the ones who fully developed these ideas 

 and forced them on a reluctant world, and most credit rightly 

 goes to them for bringing the discoveries to fruition. It is not 

 only new ideas that lead to discoveries. Indeed few ideas are 

 entirely original. Usually on close study of the origin of an 

 idea, one finds that others had suggested it or something very 

 like it previously. Charles NicoUe calls these early ideas that are 

 not at first followed up, " precursor ideas ". 



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