THE ART OF SCIENTIFIC INVESTIGATION 



giving them sufficient critical thought. Enthusiasm is a most 

 valuable stimulant but, like most stimulants, its use needs to be 

 tempered with a proper understanding of all its effects. 



If the young scientist succeeds within a year or two of 

 graduation in establishing a profitable Une of work, it is as well 

 for him to pursue it to the exclusion of other subjects, but 

 generally it is wise for him to gain some breadth of experience 

 before devoting all his time to one field. Similarly with his place 

 of work : if he is fortunate enough to find his colleagues and the 

 circumstances of his position such that he is well satisfied with 

 his advances, well and good, but often, especially if the scientist 

 feels he is getting into a groove, a change of position is very 

 helpful owing to the great stimulus that is to be had from fresh 

 mental contacts and different scientific fields. I have been struck 

 by this myself and others have told me that they also have 

 experienced it. Perhaps every three to five years the scientist 

 under forty should examine his position in this light. A change 

 of subjects also is often beneficial, for working too long on the 

 same problem can produce intellectual sterility. 



It is usually difficult or undesirable for senior scientists to 

 change their posts; for them the sabbatical year's leave provides 

 the opportunity for a change of mental climate, while another 

 method is to arrange a temporary exchange of scientists between 

 institutes. 



It is rare for a person to carry within himself enough drive 

 and interest to be able to pursue research for long if he is isolated 

 from people with similar interests. Most scientists stagnate when 

 alone, but in a group have a symbiotic-like effect on one another, 

 just as to culture some bacteria it is necessary to have a number 

 of individual organisms or to start a fire several sticks are 

 necessary. This is the main advantage of working in a research 

 centre. The fact that there one can get advice and co-operation 

 from colleagues and borrow apparatus is of secondary impor- 

 tance. Scientists from the more outlying parts of the world get 

 great benefit from coming to one of the great research centres 

 for a period of work, and also from paying brief visits to various 

 research centres. Similarly, the main value of scientific congresses 

 is the opportunity they provide for scientists to meet informally 

 and discuss topics of mutual interest. Great stimulus is to be 



156 



