286 STUDY OF NATURAL HISTORY. 
analogies ;—they darken the subject itself to which 
they are applied, whilst they diffuse over it their own 
specious colouring: hence such analogies, although 
fictitious, may be properly used by the poet or the 
orator, to ennoble, and beautify subjects which re- 
quire dignity and ornament; but they cannot for a 
moment be admitted into the precincts of physical 
science. An instance, indeed, in ordinary cases, on 
which a just analogy is founded, may in itself be 
fictitious, as in the employment of parables and fables, 
or in putting a supposed case; yet such instances, 
where science is out of the question, may be just 
analogies, because they are instances of some real 
principle obtained by previous induction, or actual 
observations embodied in some arbitrary form. They 
are, in fact, latent inductions, or philosophical truths 
divested of their proper evidence. The real difference, 
then, between an argumentative and an illustrative 
analogy, each being considered simply as such, 
consists in the form in which they are discerned. If 
each of several particulars analogically compared is 
otherwise known, and they are only brought together 
by analogy, then they are illustrations only of each 
other. But if certain particulars only are known, 
and these are employed for the investigation of 
another particular, then are the known particulars, 
arguments to the unknown one. ‘The process, how- 
ever, of detecting the justness of the analogy is the 
same in both cases. 
(197.) Analogy is in all subjects the life and soul 
of illustration. It represents to us the same general 
truth under different forms, and under different 
points of view ; and this property is in itself a fruit- 
ful source of instruction. For though the facts 
