498 OPERATIONS SUBSIDIARY TO INDUCTION. 



Classification, thus regarded, is a contrivance for the best possible order- 

 ing of the ideas of objects in our minds; for causing the ideas to accom- 

 pany or succeed one another in such a way as shall give us the greatest 

 command over our knowledge already acquired, and lead most directly to 

 the acquisition of more. The general problem of Classification, in refer- 

 ence to these purposes, may be stated as follows : To provide that things 

 shall be thought of in such groups, and those groups in such an order, as 

 will best conduce to the remembrance and to the ascertainment of their 

 laws. 



Classification thus considered, difEers from classification in the wider 

 sense, in having reference to real objects exclusively, and not to all that are 

 imaginable : its object being the due co-ordination in our minds of those 

 things only, with the properties of which we have actually occasion to make 

 ourselves acquainted. But, on the other hand, it embraces all really ex- 

 isting objects. We can not constitute any one class properly, except in 

 reference to a general division of the whole of nature ; we can not deter- 

 mine the group in which any one object can most conveniently be placed, 

 without taking into consideration all the varieties of existing objects, all at 

 least which have any degree of affinity with it. No one family of plants 

 or animals could have been rationally constituted, except as part of a sys- 

 tematic arrangement of all plants or animals ; nor could such a general ar- 

 rangement have been properly made, Avithout first determining tlie exact 

 place of plants and animals in a general division of nature. 



§ 2. There is no property of objects which may not be taken, if we 

 please, as the foundation for a classification or mental gi'ouping of those 

 objects ; and in our first attempts we are likely to select for that purpose 

 properties which are simple, easily conceived, and perceptible on a first 

 view, without any previous process of thought. Thus Tournefort's ar- 

 rangement of plants was founded on the shape and divisions of the corolla; 

 and that Avhich is commonly called the Linnaean (though Linnasus also sug- 

 gested another and more scientific arrangement) was grounded chiefly on 

 the number of the stamens and pistils. 



But these classifications, which are at first recommended by the facility 

 they afford of ascertaining to what class any individual belongs, are seldom 

 much adapted to the ends of that Classification which is the subject of our 

 present remarks. The Linnaean arrangement answers the purpose of mak- 

 ing us think together of all those kinds of plants which possess the same 

 number of stamens and pistils ; but to think of them in that manner is of 

 little use, since we seldom have any thing 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 designation would 

 conduce to our remembering those common properties so far as they were 

 ascertained, and would dispose us to be on the lookout for such of them 

 as were not yet known. But since this is not the case, the only purpose of 

 thought which the Linnaan classification serves is that of causing us to re- 

 member, 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 accu- 

 racy 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 greatei- number of properties in common, the effect of 



