166 STUDY OF NATURAL HISTORY. 
ations of nature must originate in analysis, we shall 
first intimate how this can be most successfully 
prosecuted. 
(105.) If we reflect for a moment on the sort of 
information which it is the province of natural history 
to teach, we shall find that all the knowledge of an or- 
ganised being which it is possible to acquire, is com- 
prised under one or other of the following heads : -— 
1. Its structure and composition. _ 
2. Its properties. 
3. Its relations to other beings. 
(106.) Hence it naturally follows that a knowledge 
of species is the true basis upon which the science 
reposes for its successful prosecution. We cannot 
combine objects, with due regard to their fitness, 
until we understand their structure and properties ; 
any more than we can acquire a language, before 
we become acquainted with its alphabet. 
(107.) A knowledge of structure, and of pro- 
perties, is to natural history, what experience is to 
other branches of physical science. In either case, 
we look not to causes, for they are beyond our 
comprehension ; but we look to objects or to facts, 
which every body, under favourable circumstances, 
can verify; and which, in consequence, become 
immutable truths. Upon this basis, therefore, we 
must commence the study of nature: and proceeding 
step by step,—measuring back our ground when 
we begin to doubt, yet gaining confidence from 
every corroborating evidence,—we advance from 
the foundation to the portico. 
(108.) -1. Let us first enquire what are the consi- 
derations which enter into the structure and composi- 
