Does the Old Law contain moral precepts?

It seems that the Old Law does not contain any moral precepts:

Objection 1:  As was established above (q. 91, a. 4-5), the Old Law is distinct from the law of nature.  But moral precepts belong to the law of nature.  Therefore, they do not belong to the Old Law.

Objection 2:  Divine law was supposed to assist men in cases where human reason is deficient; this is clear with those things pertaining to the Faith that lie beyond human reason.  But man’s reason seems to be sufficient for moral precepts.  Therefore, moral precepts are not part of the Old Law, which is a type of divine law.

Objection 3:  The Old Law is called “the letter that kills,” as is clear from 2 Corinthians 3:6.  But moral precepts give life and do not kill—this according to Psalm 118:93 (“I will never forget Your precepts (iustificationes), because in them You give me life.”)  Therefore, moral precepts do not belong to the Old Law.

But contrary to this:  Ecclesiasticus 17:9 says, “He gave them discipline and the law of life for an inheritance.”  But ‘discipline’ (disciplina) pertains to morals, since the Gloss on Hebrews 12:11 (“Every chastisement (disciplina) .....”) says, “Discipline involves the learning of morals through difficulties.”  Therefore, the Law given by God contained moral precepts.

I respond:  As is clear from Exodus 20:13 and 15 “You shall not kill ..... You shall not steal”), the Old Law contained certain moral precepts.  And this makes sense.  For just as the main intention of human law is to establish the friendship of men with one another, so too the intention of divine law is mainly to establish man’s friendship with God.  Now since, according to Ecclesiasticus 13:19 (“Every beast loves its like”), likeness is a reason for love, it is impossible for there to be friendship between man and God, who is absolutely good, unless men are made good.  Hence, Leviticus 19:2 says, “You will be holy, for I am holy.”  But the goodness of a man is virtue, which makes the one who has it good.  And so precepts of the Old Law had by all means to be given concerning the acts of the virtues.  And these are the moral precepts of the Law.

Reply to objection 1:  The Old Law is distinguished from the law of nature not in the sense of being altogether different from it, but in the sense of adding something to it.  For just as grace presupposes nature, so too divine law must presuppose the natural law.

Reply to objection 2:  It was appropriate for divine law to provide for man not only in those matters for which reason is insufficient for, but also in those matters concerning which man’s reason can be impeded.  Now as far as the moral precepts are concerned, man’s reason cannot be mistaken about the universal principle in the case of the most general precepts of the law of nature, but it can nonetheless, because of habitual sinning, be blinded with respect to particular actions.  On the other hand, there are many whose reason goes awry with respect to those other moral precepts that are like conclusions deduced from the most general precepts of the law of nature, with the result that many people are such that their reason judges as permissible things that are evil in themselves (mala secundum se).  Hence, man had to be given assistance, through the authority of divine law, against both kinds of error.
Similarly, in order to prevent the error of human reason that was occurring with many people, the things proposed to us for acceptance by faith (credenda) include not only some that reason cannot attain to, e.g., that God is three, but also some that right reason can attain to, e.g., that God is one.

Reply to objection 3:  As Augustine shows in De Spiritu et Littera, the letter of the law can be an occasion of ‘killing’ even in the case of the moral precepts, viz., insofar as it commands what is good without offering the assistance of grace to fulfill what it commands.