each is bound by the principles of natural justice to render to others
that assistance which is necessary to make them as happy as himself, or
which they justly owe to him in return.

§4. The _moral law_ is that which prescribes to men their duties to God
and to each other. As a rule of human conduct therefore, it corresponds
exactly to the law of nature. The moral law is briefly expressed in the
decalogue or ten commandments, and is still more briefly summed up in
the two great commandments, to love God with all our heart and to love
our neighbor as ourselves. God being its author, it is called the
_divine law_; and, being found in the Holy Scriptures, in which his will
is revealed to mankind, it is called the _revealed law_, or _law of
revelation_.

§5. _Political law_, as has been observed, is that system or form of
fundamental rules, called the constitution, by which the people in their
political capacity, or as a body politic, agree to be governed. The
nature of this law will more clearly appear from a more particular
definition of constitution, and from a description of the manner in
which a constitution is made. (Chap. V.)

§6. The word _municipal_ was used by the Romans to designate that which
related to a _municipium_, which was a free town, or city. The rights of
a citizen of such free city or town were called _municipal rights_, and
its officers were called _municipal officers_. In this country, the word
is not only used in this limited sense, but is extended to what
pertains to a state. Hence the body of laws which prescribe the duties
of the citizens of a state, are called the _municipal_ or _civil law_.
And the term is used to distinguish the laws made by the legislature, or
law-making power of the state, from the constitution, or political law,