PRELIMINARY CONSIDERATIONS. 
3 
much occupied and interested with their discoveries, to attempt innovations in the nomencla¬ 
ture. On the other hand, those who have but partial acquaintance with the philosophy of the 
subject, or with the facts, are the first to propose a reformation in the vocabulary, and from 
the want of this essential knowledge, fail in attaining the object, and leave it in a worse con¬ 
dition than before. 
No one who is aware that our present system of nomenclature had a beginning, and that 
it is an improvement upon all that preceded it, but believes likewise that another and better 
system will hereafter take its place. 
The arrangment by classes, orders, genera and species, is the only one which will enable 
man to systematize his discoveries or results, whether in individual objects or in philosophic 
truths ; and the more nearly he can adopt this mode, the more nearly has he arrived at the 
order of nature; and in the same proportion, the more accurate become the details, and 
consequently the general results. What is here true of individuals or facts, is true in like 
manner of masses ; and the application of this principle in Geology is that which is bringing 
the subject more strictly within the limits of the exact sciences, or the more exact of the 
natural sciences. 
In geological formations, the relative place of species, genera, orders, etc., with their 
subordinates, has not yet been determined. Thus we find a single rock, and a group of rocks, 
occupying the same place in the scale, or the same column in the tabular view. This at 
present is matter of necessity ; for there has not been time in all cases to make the minute 
examinations which are required, in order to pronounce where the limit of a genus or species 
should terminate ; and therefore groups, which may be either orders or genera, hold the same 
place as individual rocks which are species. 
In rocks, as in other classes of natural objects, it is often very easy to discover the generic 
limit, clearly and undoubtedly, as in Botany the oaks ; while in other cases, as in the grasses 
and flowerless plants, the most minute examination is requisite to separate genera and species. 
Subdivisions will one day be made in what are now termed groups of rocks, as have been 
in some of the obscure families of animals and plants; and it is well to bear in mind, that a 
group is composed of an assemblage of individuals, which, for want of more accurate know¬ 
ledge, are left thus, rather than hazard a division at present. A group, then, consists of an 
assemblage of individuals. A rock constitutes both the species and genus, there being no 
allied one with which it could be united to form a genus of more than one species. 
From these remarks, it is not to be understood that Geology is so much more obscure or 
doubtful than other sciences ; for subdivisions of genera and orders of plants and animals are 
constantly made, for the reasons that the individuals in question differ in essential particulars 
from the descriptive characters of their former associates. The same thing has yet to be 
done for Geology ; what now constitute groups, will be identified as consisting of several 
individuals, and separated accordingly. 
In this way only, man progresses in systematic knowledge ; at his first investigations, 
throwing together those things which bear some obvious resemblance ; and in his subsequent 
examinations, with increased knowledge, making more accurate and natural subdivisions. 
