t which, before aught else, falls
under apprehension, is _being_, the notion of which is included in
all things whatsoever a man apprehends. Wherefore the first
indemonstrable principle is that "the same thing cannot be affirmed
and denied at the same time," which is based on the notion of _being_
and _not-being:_ and on this principle all others are based, as is
stated in _Metaph._ iv, text. 9. Now as _being_ is the first thing
that falls under the apprehension simply, so _good_ is the first
thing that falls under the apprehension of the practical reason,
which is directed to action: since every agent acts for an end under
the aspect of good. Consequently the first principle of practical
reason is one founded on the notion of good, viz. that "good is that
which all things seek after." Hence this is the first precept of law,
that "good is to be done and pursued, and evil is to be avoided." All
other precepts of the natural law are based upon this: so that
whatever the practical reason naturally apprehends as man's good (or
evil) belongs to the precepts of the natural law as something to be
done or avoided.

Since, however, good has the nature of an end, and evil, the nature
of a contrary, hence it is that all those things to which man has a
natural inclination, are naturally apprehended by reason as being
good, and consequently as objects of pursuit, and their contraries as
evil, and objects of avoidance. Wherefore according to the order of
natural inclinations, is the order of the precepts of the natural
law. Because in man there is first of all an inclination to good in
accordance with the nature which he has in common with all
substances: inasmuch as every substance seeks the preservation of its
own being, according to its nature: and by reason of this
inclination, whatever is a means of preserving human life, and of
warding off its obstacles, belongs to the natural law. Secondly,
there is in man an inclination to things that pertain to him more
specially, according to that nature which he has in common with other
animals: and in virtue of this inclination, those things are said to
belong to the natural law, "which nature has taught to all animals"
[*Pandect. Just. I, tit. i], such as sexual intercourse, education of
offspring and so forth. Thirdly, there is in man an inclination to
good, according to the nature of his reason, which nature is proper
to him: thus man has a natural inclination to know the truth about