RISE AND PROGRESS OF ZOOLOGY 3 
another epoch we find that original research has 
been abandoned, and the technicalities of system 
and nomenclature alone regarded. To meet the 
first difficulty, and to preserve, nevertheless, a_ 
connected narrative, it seems advisable to treat 
the subject historically ; and pre-supposing certain 
epochs in this science, to detail the peculiar charac- 
teristics of each. This will of course lead to some 
enquiry into the merits of those who have successively 
promoted or retarded the progress of knowledge ; or 
who have been the founders of systems and methods, 
which for a time have endured, and then been laid 
aside. The revolutions of science are almost as 
frequent, and often more extraordinary, than those 
of political institutions. Both are results, not so 
much of the talents or efforts of large communities 
acting simultaneously, as of the influence of some 
one individual, whose qualities, good or bad, have 
not unfrequently worked the overthrow of laws, and 
modes of thinking, which had long been supported 
by the voice of a nation. It is, therefore, the part 
of the natural not less than of the political historian, 
to trace the causes of such revolutions, as far as 
possible, to their sources; and not to rest contented 
with the bare enumeration of the facts themselves, 
or of the results which followed. 
(3.) Nor is the above the only difficulty of the 
task before us. To estimate aright the progress of 
this science, it is essential to draw a just distinction 
between analogical research and systematic arrange- 
ment; or, in other words, between the minute in- 
vestigation of the properties and characters of an 
animal, and its subsequent arrangement among other 
B 2 
