340 PERSONAL PREPARATION FOR RESEARCH. 



versal negative into a universal affirmative ; thus, ' no 

 metals are infusible substances, ' may be transformed 

 into ' all metals are fusible substances ; ' and then into 

 'all infusible substances are not metals.' A particular- 

 negative proposition can only be converted by first chang- 

 ing it into an affirmative one, and then converting it sim- 

 ply (i.e. into exactly the same form) ; thus ' some solid 

 bodies are not transparent substances,' may be first changed 

 into 'some solid bodies are transparent bodies,' and then 

 converting it into ' some transparent substances are solid 

 bodies.' 



It is clear from these illustrations, that the proper 

 intellectual digestion of the results of new experiments and 

 observations, and even of existing scientific knowledge, is 

 an important part of original research. The illustrations 

 also show that considerable intellectual ability is necessary 

 in order to analyse, permutate, and transform scientific 

 ideas and statements into their equivalents or inclusives, 

 for the purpose of forming new propositions, and extracting 

 from them the maximum amount of knowledge; and that 

 a high degree of scientific discernment is required in order 

 to be able to perceive what is contained in the evidence, 

 and what is not. It is this faculty of scientific insight 

 which, more than any other, characterises a great scientific 

 discoverer. The faculty may be cultivated by the practice 

 of analysing scientific facts, and drawing immediate infer- 

 ences, in the manner already shown ; and it would be good 

 experience for a young experimentalist to ascertain how 

 much knowledge he could extract by such means from 

 given scientific statements. 



The illustrations also show, that although the process 

 of reasoning does not empower us to create new truths, it 

 enables us to render explicit, and thus to convert into avail- 

 able knowledge, truths which were previously locked up in a 



