there is no
hindrance to there being some things in common to all other animals, and
some common both to men and beasts, since the nature of all is common. But
that highest and chief good and evil which we are in search of, is
distributed and divided among the different kinds of animals, each having
its own peculiar good and evil, adapted to that end which the nature of
each class of animal requires. Wherefore, when we say that the chief good
to all animals is to live according to nature, this must be understood as
if we said that they had all the same chief good. But as it may truly be
said to be common to all arts to be conversant about some science, and
that there is a separate science belonging to each art, so we may say that
it is common to all animals to live according to nature, but that there
are different natures; so that the horse has by nature one chief good, the
ox another, man another; and yet in all there is one common end; and that
is the case too, not only in animals, but also in all those things which
nature nourishes, causes to grow, and protects; in which we see that those
things which are produced out of the earth, somehow or other by their own
energy create many things for themselves which have influence on their
life and growth, and so each in their own kind they arrive at the chief
good. So that we may now embrace all such in one comprehensive statement;
and I need not hesitate to say, that every nature is its own preserver;
and has for its object, as its end and chief good, to protect itself in
the best possible condition that its kind admits of; so that it follows
inevitably that all things which flourish by nature have a similar but
still not the same end. And from this it should be understood, that the
chief and highest good to man is to live according to nature which we may
interpret thus,--to live according to that nature of a man which is made
perfect on all sides, and is in need of nothing. These things then we must
explain; and if our explanation is rather minute, you will excuse it; for
we are bound to consider the youth of our hearer, and the fact that he is
now perhaps listening to such a discourse for the first time. Certainly,
said I; although what you have said hitherto might be very properly
addressed to hearers of any age.

X. Since then, said he, we have explained the limit of those things which
are to be desired, we must next show why the facts are as I have stated
them. Wherefo