212 Professor Necker on Mineralogy considered 



pile, after the complete decomposition of the mineral, are indis- 

 pensable, and even in many cases would be unavailing, the con- 

 stituent parts having never been entirely decomposed, and be- 

 ing supposed to be compound bodies merely by analogy ? 



§ 3. 9d^ The number of the characters enumerated in 

 the classes which are the iirst or higher divisions of each 

 of the two organic kingdoms, are to be considered as be- 

 longing in common to all the animals and vegetables, forming 

 by their assemblage these great classes or divisions. Their 

 number is considerable, and their importance great. In low- 

 er divisions, as in orders, or families, or genera, the charac- 

 ters become gradually less numerous and important ; till at 

 length some few almost unimportant characters, prefixed to 

 each species, complete the description of each animal or vege* 

 table, and thus terminate by real definition the enumeration of 

 all the similitudes and diff'erences by which this animal or vege- 

 table is connected to, or separated from, all the other beings of 

 the same department of nature. Hence arises, in courses of 

 lectures given according to the natural classification, that rich 

 and highly interesting display of analogies, and of facts common 

 to an immense number of beings, which characterize the higher 

 divisions of the subject in zoology and in botany; while the far 

 less important details of discrimination between the genera or 

 the species can be left, without any inconvenience by the pro- 

 fessor, to the private study of the pupil. This is far from be- 

 ing the case with the present mineralogical methods of classifica* 

 tion. A single fact — a single abstract property — is often the 

 only common character which binds together, in the form of a 

 class, an order, or a family, a large multitude of minerals other- 

 wise entirely different in the remainder of their properties. The 

 very name of a class contains often all that is common to all the 

 beings of which it is composed. But, by a most melancholy com- 

 pensation, the lower subdivisions, the species and varieties, re- 

 quire to be distinguished from each other by the accumulation 

 of so many, and often uninteresting details, that the professor 

 who speaks, and the student who listens, become fatigued and 

 dissatisfied with the long enumeration of almost individual be- 

 ings, which composes now the greatest part of a course of lec- 

 tures on mineralogy. What, for instance, could be said which 



