still too imperfect to justify any such use of it. His divisions into
Apathetic, Sensitive, and Intelligent animals are entirely theoretical. He
places, for instance, Fishes and Reptiles among the Intelligent animals,
as distinguished from Crustacea and Insects, which he refers to the second
division. But one would be puzzled to say how the former manifest more
intelligence than the latter, or why the latter should be placed among the
Sensitive animals. Again, some of the animals that he calls Apathetic have
been proved by later investigators to show an affection and care for their
young, seemingly quite inconsistent with the epithet he has applied to
them. In fact, we know so little of the faculties of animals that any
classification based upon our present information about them must be very
imperfect.

Many modifications of Cuvier's great divisions have been attempted. Some
naturalists, for instance, have divided off a part of the Radiates and
Articulates, insisting upon some special features of structure, and
mistaking these for the more important and general characteristics of
their respective plans. All subsequent investigations of such would-be
improvements show them to be retrograde movements, only proving more
clearly that Cuvier detected in his four plans all the great structural
ideas on which the vast variety of animals is founded. This result is of
greater importance than may at first appear. Upon it depends the question,
whether all such classifications represent merely individual impressions
and opinions of men, or whether there is really something in Nature that
presses upon us certain divisions among animals, certain affinities,
certain limitations, founded upon essential principles of organization.
Are our systems the inventions of naturalists, or only their reading of
the Book of Nature? and can that book have more than one reading? If these
classifications are not mere inventions, if they are not an attempt to
classify for our own convenience the objects we study, then they are