370 THE PRINCIPLES OF SCIENCE. 



dently assign them by mere contemplation of the combina- 

 tions, as given in the first group. Several tentative classi- 

 fications must probably be made before we can resolve the 

 question. Let us now suppose that instead of seven objects 

 and five qualities, we have, say, five hundred objects and 

 fifty qualities. If we were to attempt the same method of 

 exhaustive grouping which we before employed, we should 

 have to arrange the five hundred objects in fifty different 

 ways, before we could be sure that we had discovered even 

 the simpler laws of correlation. But even the successive 

 grouping of all those possessing each of the fifty properties 

 would not necessarily give us all the laws. There might 

 exist complicated relations between several properties 

 simultaneously, for the detection of which no rule of pro- 

 cedure whatever can be given. 



If the reader entertains any doubt as to the difficulty 

 of classifying combinations so as to disclose their rela- 

 tions, let him test the matter practically upon the fol- 

 lowing series of combinations. They involve only six 

 letters denoting six qualities, which are subject to four 

 laws of correlation of no great complexity. 



ABCDEF ABcDe/ 



ABCDeF Abcdftf 



ABCDe/ aBcDEF 



ABCdE/ aBcDeF 



ABcDEF aBcDe/ 



ABcDeF a&cdE/ 



I shall be happy to receive the solution of the above 

 problem in classification from any reader who thinks he 

 has solved it ; that is to say, I shall be glad to ascer- 

 tain whether any reader succeeds in detecting the laws 

 of correlation between the letters, which yield the above 

 combinations, according to the principles of the Indirect 

 Method described in Chapter VI. 



