CLASSIFICATION. 309 



ABCdE 



ABcde aBcde 



A6CDE a&CDE 



AbcDe abcDe. 



They are now classified, so that those containing A stand 

 first, and those devoid of A second, but no other property 

 seems to be correlated with A. Let us alter this arrange- 

 ment and group the combinations as follows : 



ABCdE A&CDE 



ABcde AbcDe 



aBCdE a&CDE 



aEcde abcDe. 



It requires very little examination to discover that, in the 

 first group, B is always present and D absent, whereas in 

 the second group, B is always absent and D present. This 

 is the result which follows from a law of the form B = d 

 (see vol. i. p. 157), so that in this mode of arrangement 

 we readily discover a close correlation between two letters. 

 Altering the groups again as follows : 



ABCcZE ABcde 



aBCdE aBcde 



A&CDE AbcDe 



a&CDE abcDe, 



we discover another evident correlation between C and E. 

 Between A and the other letters, or between the two pairs 

 of letters B, D and 0, E there is no logical connexion 

 whatever. 



This example may perhaps seem tedious, but it will be 

 found instructive in this way. We are classifying only 

 seven objects or combinations, in each of which only five 

 qualities are considered. There are only two laws of cor- 

 relation between four of those five qualities, and those 

 laws are of the simplest logical character. Yet the reader 

 would hardly discover what those laws were, and confi- 

 VOL. n. B b 



