ding false
testimony, is added the prohibition against false judgment, according
to Ex. 23:2: "Neither shalt thou yield in judgment, to the opinion of
the most part, to stray from the truth"; and the prohibition against
lying (Ex. 23:7): "Thou shalt fly lying," and the prohibition against
detraction, according to Lev. 19:16: "Thou shalt not be a detractor,
nor a whisperer among the people." To the other two commandments no
further precepts are added, because thereby are forbidden all kinds
of evil desires.

Reply Obj. 1: The precepts of the decalogue are ordained to the love
of God and our neighbor as pertaining evidently to our duty towards
them; but the other precepts are so ordained as pertaining thereto
less evidently.

Reply Obj. 2: It is in virtue of their institution that the
ceremonial and judicial precepts are determinations of the precepts
of the decalogue, not by reason of a natural instinct, as in the case
of the superadded moral precepts.

Reply Obj. 3: The precepts of a law are ordained for the common good,
as stated above (Q. 90, A. 2). And since those virtues which direct
our conduct towards others pertain directly to the common good, as
also does the virtue of chastity, in so far as the generative act
conduces to the common good of the species; hence precepts bearing
directly on these virtues are given, both in the decalogue and in
addition thereto. As to the act of fortitude there are the order to
be given by the commanders in the war, which is undertaken for the
common good: as is clear from Deut. 20:3, where the priest is
commanded (to speak thus): "Be not afraid, do not give back." In like
manner the prohibition of acts of gluttony is left to paternal
admonition, since it is contrary to the good of the household; hence
it is said (Deut. 21:20) in the person of parents: "He slighteth
hearing our admonitions, he giveth himself to revelling, and to
debauchery and banquetings."
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TWELFTH ARTICLE [I-II, Q. 100, Art. 12]

Whether the Moral Precepts of the Old Law Justified Man?

Objection 1: It would seem that the moral precepts of the Old Law
justified man. Because the Apostle says (Rom. 2:13): "For not the
hearers of the Law are justified before God, but the doers of the Law
shall be justified." But the doers of the Law are those who fulfil
the precepts of the Law. Therefore the fulfilling of the precepts of
the Law was a cause of justification.

Obj. 2: Further, it is