74 THE HISTORY OF SCIENCE 



mental procedure involved in invention and in the 

 discovery of truth can be successfully imparted by 

 instruction. The individuality of the man of genius 

 engaged in investigation must remain a factor diffi- 

 cult to analyze. Bacon, whose purpose was to hasten 

 man's empire over nature through increasing the 

 number of inventions and discoveries, recognized 

 that the method he illustrated is not the sole method 

 of scientific investigation. In fact, he definitely states 

 that the method set forth in the Novum Organum 

 is not original, or perfect, or indispensable. He was 

 aware that his method tended to the ignoring of 

 genius and to the putting of intelligences on one level. 

 He knew that, although it is desirable for the inves- 

 tigator to free his mind from prepossessions, and to 

 avoid premature generalizations, interpretation is the 

 true and natural work of the mind when free from 

 impediments, and that the conjecture of the man of 

 genius must at times anticipate the slow process of 

 painful induction. As we shall see in the nineteenth 

 chapter, the psychology of to-day does not know 

 enough about the workings of the mind to prescribe 

 a fixed mental attitude for the investigator. Never- 

 theless, Bacon was not wrong in pointing out the 

 virtues of a method which he and many others turned 

 to good account. Let us first glance, however, at the 

 activities of those scientists who preceded Bacon in 

 the employment of the experimental method. 



Gilbert relied, in his investigations, on oft-repeated 

 and verifiable experiments, as can be seen from his 

 work De Magnete. He directs the experimenter, for 

 example, to take a piece of loadstone of convenient 

 size and turn it on a lathe to the form of a ball. It 



