302 OPERATIONS SUBSIDIARY TO INDUCTION. 



would dispose us to be on the look-out for such of 

 them as are not yet known. But since this is not the 

 case, the only purpose of thought which the Linnaean 

 classification serves is that of causing us to remember, 

 better than we should otherwise have done, the exact 

 number of stamens and pistils of every species of 

 plants. Now, as this property is of little importance 

 or interest, the remembering it with any particular 

 accuracy is of no moment. And inasmuch as, by 

 habitually thinking of plants in those groups, we are 

 prevented from habitually thinking of them in groups 

 which have a greater number of properties in common, 

 the effect of such a classification, when systematically 

 adhered to, upon our habits of thought, must be 

 regarded as mischievous. 



The ends of scientific classification are best 

 answered, when the objects are formed into groups 

 respecting which a greater number of general propo- 

 sitions can be made, and those propositions more 

 important, than could be made respecting any other 

 groups into which the same things could be distri- 

 buted. The properties, therefore, according to which 

 objects are classified, should, if possible, be those which 

 are causes of many other properties ; or at any rate, 

 which are sure marks of them. Causes are preferable, 

 both as being the surest and most direct of marks, 

 and as being themselves the properties upon which it 

 is of most use that our attention should be strongly 

 fixed. But the property which is the cause of the 

 chief peculiarities of a class, is unfortunately seldom 

 fitted to serve also as the diagnostic of the class. 

 Instead of the cause, we must generally select some 

 of its more prominent effects, which may serve as 

 marks of the other effects and of the cause itself. 



A classification thus formed is properly scientific 



