4 
INTEODUCTOKY LETTER. 
free the intellect chained in the narrow bounds of artifi- 
cial methods, we should early fix the attention of the young 
naturalist on the universality of these views, and accustom 
him to seize, at a single glance, all the features which, by 
their union, form the peculiar character of each indivi- 
dual. 
My own attempts, and the example of my predecessors, 
have proved to me that the artificial method can be em- 
ployed with less success in the reptiles than in other classes 
of animals ; and that, in following such principles, we shall 
never be able to give this science that clearness so essential 
to the beginner. In the publication of my labours, then, 
I lay down as a rule, to trace, in a few words, a faithful 
portrait of each species, considered in its different relations 
to allied species, to indicate the passage of one imaginary 
group to another, and to reduce the science to its most 
simple objects: such is the object of my classification. To 
attain this end, without introducing innovations, I have 
availed myself, as respects the nomenclature, of the materials 
which I have found in the works of my predecessors. I hope 
that philosophers will agree with me in this ; for what me- 
mory is capable of mastering the nomenclature of even a 
single class of the animal kingdom, and of making it avail- 
able in the study of Nature ? In what confusion have not 
modern naturalists plunged the most beautiful of the 
sciences, by erecting those unintelligible systems, the sole 
merit of which often resolves itself into a mere parade of 
words, which dazzle instead of enlightening. Such systems 
appear to me made only for their authors, and miss their aim, 
which should be to guide the student, until he be tempted 
to persuade himself that systems do not exist in nature. 
Yet these modern artificial methods are not themselves 
proof against a rigorous examination ; they are far from 
having established what is meant by species and genus. 
Slight differences of form in some isolated part, due often 
either to accident or to the influence of different climates, 
have often induced naturalists to divide a species into sub- 
species, and to designate each by a special epithet ; some 
of these imaginary species united, form sections which they 
are pleased to denominate sub-genera, although they are 
