Extract of the Vol. II

As air and water are supplied to animals in sufficient profusion, the three 
great objects of desire, which have changed the forms of many animals by their 
exertions to gratify them, are those of lust, hunger, and security. A great want 
of one part of the animal world has consisted in the desire of the exclusive 
possession of the females, and these have acquired weapons to combat each other 
for this purpose, as the very thick, shield-like, horny skin on the shoulder of 
the boar is a defence only against animals of his own species, who strike 
obliquely upwards, nor are his tushes for other purposes, except to defend 
himself, as he is not naturally a carnivorous animal. So the horn of the stag 
are sharp to offend his adversary, but are branched for the purpose of parrying 
or receiving the thrusts of horns similar to his own, and have therefore been 
formed for the purpose of combating other stags for the exclusive possession of 
the females ; who are observed, like the ladies in the times of chivalry, to 
attend the car of the victor.
 

The birds, which do not carry food to their young, and, do not therefore marry, 
are armed