On The Parts Of Animals   

delivered their blow with the greatest force, whereas on the head they
occupy the weakest part of the whole body. Momus was but dull-sighted
in making this hostile criticism. For had the horns been set on the
shoulders, or had they been set on any other part than they are, the
encumbrance of their weight would have been increased, not only
without any compensating gain whatso::ver, but with the disadvantage
of impeding many bodily operations. For the point whence the blows
could be delivered with the greatest force was not the only matter to
be considered, but the point also whence they could be delivered with
the widest range. But as the bull has no hands and cannot possibly
have its horns on its feet or on its knees, where they would prevent
flexion, there remains no other site for them but the head; and this
therefore they necessarily occupy. In this position, moreover, they
are much less in the way of the movements of the body than they would
be elsewhere.
Deer are the only animals in which the horns are solid throughout, and
are also the only animals that cast them. This casting is not simply
advantageous to the deer from the increased lightness which it
produces, but, seeing how heavy the horns are, is a matter of actual
necessity.
In all other animals the horns are hollow for a certain distance, and
the end alone is solid, this being the part of use in a blow. At the
same time, to prevent even the hollow part from being weak, the horn,
though it grows out of the skin, has a solid piece from the bones
fitted into its cavity. For this arrangement is not only that which
makes the horns of the greatest service in fighting, but that which
causes them to be as little of an impediment as possible in the other
actions of life.
Such then are the reasons for which horns exist; and such the reasons
why they are present in some animals, absent from others.
Let us now consider the character of the material nature whose
necessary results have been made available by rational nature for a
final cause.
In the first place, then, the larger the bulk of animals, the greater
is the proportion of corporeal and earthy matter which they contain.
Thus no very small animal is known to have horns, the smallest horned
animal that we are acquainted with being the gazelle. But in all our
speculations concerning nature, what we have to consider is the
general rule; for that is natural which applies either universally or
generally. And thus when we say that the largest animals have most
earthy matter, we say so because such is the general rule. Now this
earthy matter is used in the animal body to form bone. But in the
larger animals there is an excess of it, and this excess is turned by
nature to useful account, being converted into weapons of defence.
Part of it necessarily flows to the upper portion of the body, and
this is allotted by her in some cases to the formation of tusks and
teeth, in others to the formation of horns. Thus it is that no animal
that has horns has also front teeth in both jaws, those in the upper
jaw being deficient. For nature by subtracting from the teeth adds to
the horns; the nutriment which in most animals goes to the former
being here spent on the augmentation of the latter. Does, it is true,
have no horns and yet are equally deficient with the males as regards
the teeth. The reason, however, for this is that they, as much as the
males, are naturally horn-bearing animals; but they have been stripped
of their horns, because these would not only be useless to them but
actually baneful; whereas the greater strength of the males causes
these organs, though equally useless, to be less of an impediment. In
other animals, where this material is not secreted from the body in
the shape of horns, it is used to increase the size of the teeth; in
some cases of all the teeth, in others merely of the tusks, which thus
become so long as to resemble horns projecting from the jaws.
So much, then, of the parts which appertain to the head.
Part 3
Below the head lies the neck, in such animals as have one. This is the