INTRODUCTORY LETTER. 
3 
ceptation ; it also signifies the total impression which the 
whole of any being makes on us, — an impression which we 
may feel, but which it is impossible to express in words : 
it is the result of the harmony of all the isolated parts, and 
their mutual relations, which is comprehended at a glance. 
We retain it as a whole, without being able to give an ac- 
count of the properties of each of them taken singly. All 
the existences of Nature, be they animals, plants, or even 
inanimate objects, make on us this impression ; but it is 
the more difficult to be analyzed, as the beings we examine 
are more complicated, for the more their nature is elevated, 
the more do the different characters lose themselves in the 
harmony of the whole. One of the most essential points 
of the mark at which the zoologist aims, appears to me to 
analyze this harmony, and to indicate each characteristic 
trait in relation to the whole. Yet, our modern methods 
conduct us in a path precisely opposed to that which I 
point out. The example of the illustrious author of the 
Systema Naturce^ falsely interpreted, has even sanctioned 
the practice of circumscribing the knowledge of beings in 
general, to such characteristics as are obvious on the first 
aspect. 
In examining a series of living animals, the attentive 
observer will remark, that, in their features, in their looks, 
and even in their forms, he may trace the expression of 
certain dispositions, habits, and passions, which are still 
more directly than in man the result of organization. 
On reiterating his observations, he will not fail to recognise 
by their features the different species of animals ; he will 
seize the relations which link the species to each other ; he 
will bring them together, and in this synthetic process, 
he will arrive at a natural method. A series of beings 
thus grouped, will produce an impression of the whole si- 
milar to what he would receive from a single individual, 
—an impression which it is necessary to depict as a whole, 
to obtain a knowledge of its principal features. 
This manner of examining nature is, indeed, diametri- 
cally opposed to that which sets out to distinguish indi- 
viduals from some isolated characters ; but, as it offers the 
only means of tracing a faithful picture of nature, as it sets 
