CLASSIFICATION. 499 



such a classification, when systematically adhered to, upon our habits of 

 thouglit, 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 prop- 

 ositions can be made, and those propositions 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 prop- 

 erties ; or, at any rate, which are sure marks of them. Causes are prefera- 

 ble, both as being the surest and most direct of marks, and as being them- 

 selves 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 pecul- 

 iarities of a class, is unfortunately seldom fitted to serve also as the diag- 

 nostic 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 pi-operly scientific or philosophical, and 

 is commonly called a Natural, in contradistinction to a Technical or Arti- 

 ficial, classification or arrangement. The phrase Natural Classification 

 seems most peculiai'ly appropriate to such arrangements as correspond, in 

 the groups which they form, to the spontaneous tendencies of the mind, 

 by placing together the objects most similar in their general aspect ; in op- 

 position to those technical systems which, arranging things according to 

 their agreement in some circumstance arbitrarily selected, often throw into 

 the same group objects which in the general aggregate of their properties 

 present no resemblance, and into different and remote groups, others which 

 have the closest similarity. It is one of the most valid recommendations 

 of any classification to the character of a scientific one, that it shall be a 

 natural classification in this sense also ; for the test of its scientific charac- 

 ter is the number and importance of the properties which can be asserted 

 in common of all objects included in a group; and properties on which the 

 general aspect of the things depends are, if only on that ground, impor- 

 tant, as well as, in most cases, numerous. But, though a strong recommen- 

 dation, this circumstance is not a sine qua noii; since the most obvious 

 properties of things may be of trifling importance compared with others 

 that are not obvious. I have seen it mentioned as a great absurdity in 

 the Linnwan classification, that it places (which by-the-way it does not) 

 the violet by the side of the oak ; it certainly dissevers natural affinities, 

 and brings together things quite as unlike as the oak and the violet are. 

 But the difference, apparently so wide, which renders the juxtaposition of 

 those two vegetables so suitable an illustration of a bad arrangement, de- 

 pends, to the common eye, mainly on mere size and texture ; now if we 

 made it our study to adopt the classification which would involve the least 

 peril of similar rapprochements, we should return to the obsolete division 

 into trees, shrubs, and herbs^ which though of primary importance with re- 

 gard to mere general aspect, yet (compared even with so petty and unob- 

 vious a distinction as that into dicotyledons and monocotyledons) answers 

 to so few differences in the other properties of plants, that a classification 

 founded on it (independently of the indistinctness of the lines of demarka- 

 tion) would be as completely artificial and technical as the Linnaean. 



Our natural groups, therefore, must often be founded not on the obvi- 

 ous but on the unobvious properties of things, when these are of greater 

 importance. But in such cases it is essential that there should be some 



