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various important subjects in Mineralogy . 
the same, or present gradations which form continuous series. 
The process of joining the series of characters together, is not 
only the general form of obtaining the development of this 
idea, but is also applicable to every particular case. The second 
is the representation of the species as a whole , which might, 
with great propriety, be called its original representation. The 
third is the characters of the species, by which the individuals 
contained in it may be distinguished from the individuals of 
other species. The fourth is the general description of the spe- 
cies, the object of which is to produce a distinct image of it, 
though we do not immediately inspect any of the varieties of 
the species. 
That department of Natural History which embraces all these 
subjects, and may be more particularly said to be the philoso- 
phical part of the science, is called the Theory of the System , 
because it is the system which not only contains all those ideas 
and representations, but whose usefulness also can only be judged 
of from the quality of those ideas. 
We must observe here, in the first place, that all these ideas 
and observations in general, refer exclusively to the natural-his- 
torical properties, because the science of mineralogy itself does not 
take notice of any other properties ; secondly, That there is no 
production of nature which, as an individual body, corresponds 
to those ideas, the only idea which has an object corresponding 
to it being that of an individual. Hence in nature we find only 
individuals, either simple, or compound, or mixed, but we do 
not find species, or genera, or orders ; and we must produce 
these ideas ourselves, in order to be able to develope Natural 
History as a science. In so far, a system sprung from these 
ideas might be called an artificial system, in opposition to a 
natural one. This, however, would then require to have all its 
general ideas represented by natural bodies , which does not take 
place. Individuals belonging to one species, or to one genus, 
&c., that is to say, which may be collected within that species, 
genus, &c., are the only things with which we meet in nature, 
and not those unities themselves. The latter would indeed be 
as little subject to differences of opinion or to dispute as the in- 
dividual itself, if they were to be found in nature, or existed as 
natural productions. Hence there is no such thing as a System 
