HOW TO THINK 



decisions, as tested by their results, remembering that 

 the best judgment sometimes errs, but that good judg- 

 ment does not permit the same error over and over. 

 All such analysis, it may be added, is but a special case 

 within the general rule of being guided by experience. 



Most of all will you benefit if you have opportunity to 

 generalise this rule by taking specific training in some 

 department of experimental science, such as bacteri- 

 ology or physics or chemistry. When, for example, 

 your training in the laboratory has enabled you to take 

 a minute quantity of some chemical and pass it through 

 one process after another, producing it now in solution, 

 now as a salt, now as a fused metal, now as a compound ; 

 returning it at last, perhaps after days of manipulation, 

 to its original state the same in quantity to the thou- 

 sandth of a grain, as before, nothing more, nothing 

 less; when you have learned to make such a manipula- 

 tion as this you will have taken a lesson both in accuracy 

 of method and in severe logicality of reasoning from 

 cause to effect, which will be far more valuable as a 

 mental method than any mere knowledge of chemical 

 processes involved in your study. Here, indeed, as 

 I see it, lies the real value of scientific training. The 

 student who at the end of such manipulation as I have 

 just outlined, finds that his chemical has lost the thou- 

 sandth of a grain or so, knows that there is no question 

 of "luck" involved in that. He has carelessly spilled a 

 drop or two of one of his solutions, or he has failed to 

 rinse out the last dregs of a beaker. 



And as here in the laboratory, so in the great game of 

 life, in the long run there is no such thing as "luck." 



[us] 



