140 THE PRINCIPLES OF SCIENCE. 



from certain conditions, laws, or identities governing the 

 combinations of qualities, we may deduce the nature of 

 the combinations agreeing with those conditions. Our 

 work has been to unfold the results of what is contained 

 in any statements, and the process has been one of Syn 

 thesis. The terms or combinations of which the character 

 has been determined have usually, though by no means 

 always, involved more qualities, and therefore, by the 

 relation of extension and intension, fewer objects than 

 the terms in which they were described. The truths 

 inferred were thus usually less general than the truths 

 from which they were inferred. 



In induction all is inverted. The truths to be ascer 

 tained are more general than the data from which they 

 are drawn. The process by which they are reached is 

 analytical, and consists in separating the complex com 

 binations in which natural phenomena are presented to 

 us, and determining the relations of separate qualities. 

 Given events obeying certain unknown laws, we have to 

 discover the laws obeyed. Instead of the comparatively 

 easy task of finding what effects will follow from a given 

 law, the effects are now given and the law is required. 

 We have to interpret the will by which the conditions of 

 creation were laid down. 



Induction an Inverse Operation. 



I have already asserted that induction is the inverse 

 operation of deduction, but the difference is one of such 

 great importance that I must dwell upon it. There are 

 many cases where we can easily and infallibly do a certain 

 thing but may have much trouble in undoing it. A per 

 son may walk into the most complicated labyrinth or the 

 most extensive catacombs, and turn hither and thither at 

 his will ; it is when he wishes to return that doubt and 



