Vlll PREFACE. 



matter merely of time and labour only, nor to pretend that 

 important discoveries can be completely made by rule 

 alone. My purpose is only to show that an art of scien- 

 tific discovery is much more possible now than it was in 

 the time of Lord Bacon, and is fast becoming more so, 

 and that the process of scientific discovery can even now 

 be much more completely reduced to order and rule than 

 is usually supposed. 



The process of scientific discovery depends on a com- 

 bination of experiment and logical inference ; and the 

 small success of previous writers respecting it has, in my 

 opinion, been due to the circumstance, that those who 

 possessed both the experimental and the logical know- 

 ledge necessary, made no sufficiently persistent attempt to 

 determine how far the work of scientific discovery may be 

 reduced to an art. 



To some the very proposal to write a book on such 

 a subject may appear presumptuous ; and even among 

 scientific investigators there are those who consider that 

 the methods of discovery are incommunicable. But ori- 

 ginal scientific research is not a supernatural operation. 

 If it were, it would not be possible to make discoveries by 

 means of our natural faculties, nor to communicate them 

 by ordinary means. It is a natural process, and, being 

 such, it must have laws according to which it operates. 

 It is effected by means of our mental powers, and is there- 

 fore subject to the rules of mental action, and is commu- 

 nicable by ordinary natural methods. It is also being 

 reduced, as knowledge advances, to rules of action, and will 

 in time become one of the noblest of all intellectual em- 



