268 OPERATIONS SUBSIDIARY TO INDUCTION. 



in that manner is of little use, since we seldom have anything 

 to affirm in common of the plants which have a given number 

 of stamens and pistils. If plants of the class Pentandria, 

 order Monogynia, agreed in any other properties, the habit of 

 thinking and speaking of the plants under a common designa 

 tion would conduce to our remembering those common pro 

 perties so far as they were ascertained, and would dispose us 

 to be on the look-out for such of them as were not yet known. 

 But since this is not the case, the only purpose of thought 

 which the Linnsean 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 mis 

 chievous. 



The ends of scientific classification are best answered, when 

 the objects are formed into groups respecting which a greater, 

 number of general propositions can be made, and those pro 

 positions more important, than could be made respecting any 

 other groups into which the same things could be distributed. 

 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 

 on 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. 



A classification thus formed is properly scientific or philo 

 sophical, and is commonly called a Natural, in contradistinc- 



