1). Irrational
creatures, however, do not partake thereof in a rational manner,
wherefore there is no participation of the eternal law in them,
except by way of similitude.
________________________

THIRD ARTICLE [I-II, Q. 91, Art. 3]

Whether There Is a Human Law?

Objection 1: It would seem that there is not a human law. For the
natural law is a participation of the eternal law, as stated above
(A. 2). Now through the eternal law "all things are most orderly," as
Augustine states (De Lib. Arb. i, 6). Therefore the natural law
suffices for the ordering of all human affairs. Consequently there is
no need for a human law.

Obj. 2: Further, a law bears the character of a measure, as stated
above (Q. 90, A. 1). But human reason is not a measure of things, but
vice versa, as stated in _Metaph._ x, text. 5. Therefore no law can
emanate from human reason.

Obj. 3: Further, a measure should be most certain, as stated in
_Metaph._ x, text. 3. But the dictates of human reason in matters of
conduct are uncertain, according to Wis. 9:14: "The thoughts of
mortal men are fearful, and our counsels uncertain." Therefore no law
can emanate from human reason.

_On the contrary,_ Augustine (De Lib. Arb. i, 6) distinguishes two
kinds of law, the one eternal, the other temporal, which he calls
human.

_I answer that,_ As stated above (Q. 90, A. 1, ad 2), a law is a
dictate of the practical reason. Now it is to be observed that the
same procedure takes place in the practical and in the speculative
reason: for each proceeds from principles to conclusions, as stated
above (ibid.). Accordingly we conclude that just as, in the
speculative reason, from naturally known indemonstrable principles,
we draw the conclusions of the various sciences, the knowledge of
which is not imparted to us by nature, but acquired by the efforts of
reason, so too it is from the precepts of the natural law, as from
general and indemonstrable principles, that the human reason needs to
proceed to the more particular determination of certain matters.
These particular determinations, devised by human reason, are called
human laws, provided the other essential conditions of law be
observed, as stated above (Q. 90, AA. 2, 3, 4). Wherefore Tully says
in his _Rhetoric_ (De Invent. Rhet. ii) that "justice has its source
in nature; thence certain things came into custom by reason of their
utility; afterwards these things which emanated from nature and were
approve