THEOltY OF THE SYSTEM. . 



great aim, which is the discovery of truth, perhaps hidden 

 for ever, if we endeavour to arrive at it according to any 

 other method. 



. 226. MINERAL KINGDOM. 



The Mineral Kingdom is represented by a Se- 

 ries of Natural Historical Genera. 



The object of mineralogy in producing its higher degrees 

 of classification, is first, to acquire a clear idea of the Mineral 

 Kingdom, which consists in a general survey of all its pro- 

 ductions ; and secondly, to become capable of collecting 

 every one of these productions with facility and security, 

 under the above mentioned ideas. 



If we examine the systems of Natural History, we find 

 that for the most part they are founded upon the idea of 

 a series. Yet it is difficult to decide, whether in the mi- 

 neral systems this is a series of genera or of species : for- 

 in these systems both genus and species are founded upon 

 reasons so uncertain, that it becomes utterly impossible to 

 derive any clear idea from the existence of their determi- 

 nations. A series of species is in direct opposition with that 

 of a series of genera, in fact to the idea of the genus itself, in 

 as much as it supposes that there exist no equal degrees of 

 resemblance among different species. In order to convince 

 ourselves in this respect, the best contrivance will be, to 

 produce a series of species in nature, in which those placed 

 nearest must resemble each other most, and where we may 

 begin at any chosen member. Evidently for this process a 

 single variety cannot represent the species, but we must 

 employ the whole species as completely known as pos- 

 sible. In endeavouring to produce a series of this kind, 

 very soon we shall meet with species which render it 

 doubtful whether the one or the other, or even a third, 

 a fourth, &c. should follow the preceding species ; and 

 at last we must either entirely abandon the experiment 

 or we must suppose that two, three, or more spe- 



