182 STUDY OF NATURAL HISTORY. 
enquiries which concern the natural history of an 
animal ; namely, its relation to other beings. The 
very dissimilar forms which nature has given to 
most of the great divisions of the animal world are 
so striking in themselves, that the more general re- 
lationships are obvious to common observers. Thus, 
a quadruped, a bird, a fish, or an insect, is known, 
in ordinary cases, at first sight. Even if we de- 
scend to more particulars, and proceed to assort 
quadrupeds, for instance, into separate divisions, 
we see plainly that a lion has no affinity with an ox, 
or a monkey with a mouse, further than, as being 
quadrupeds, they have a greater relation to each 
other than with birds, fishes, or insects. Relations, 
therefore, are either general or particular ; but both 
terms are used comparatively. Thus we may say 
that the elephant is related to the ox, by being in 
the same natural order: but this relation, compara- 
tively speaking, is only general; because, between 
these two quadrupeds, other forms or species inter- 
vene, which show a more particular resemblance to 
one or to the other. Hence we see that, as there are 
different degrees of relationships, it becomes neces- 
sary to give a more precise analysis of the term, 
and to ascertain in what manner these different 
degrees of relationship can be defined. 
(124.) Relations or resemblances, in the ordinary 
acceptation of the words, have long been considered 
as of two kinds, expressed by the terms analogy and 
affinity. By the first, we understand an external re- 
semblance or similitude to another object, which is 
nevertheless different in its form, structure, habits, 
or some other important circumstance: here the re- 
