Is there an appropriate number of
precepts in the Decalogue?
It seems that there is an inappropriate
number of precepts in the Decalogue:
Objection 1: As Ambrose
says, “Sin is a transgression of divine law and disobedience
against the heavenly commandments.” But sins are
distinguished from one another by whether a man sins
against God, against his neighbor, or against himself.
Therefore, since among the precepts of the Decalogue
there are none that order a man toward himself, but
only ones that order him toward God and toward his neighbor,
it seems that there is an insufficient number of precepts
in the Decalogue.
Just as the observance of the Sabbath had to do with the
worship of God, so also did the observance of the other
solemn feasts (solemnitates) and the immolation of
sacrifices. But among the precepts of the Decalogue there
is a single precept having to do with the observance of
the Sabbath. Therefore, there should also be some
precepts having to do with the other solemn feasts and
with the rite of sacrifices.
Just as one can sin against God by perjuring himself, so
too he can sin against God by blasphemy or by various
deceptions that are opposed to divine teaching. But there
is a single precept forbidding perjury, when it says, “You
shall not take the name of the Lord your God in vain.”
Therefore, the sins of blasphemy and false teaching should
be prohibited by some precept of the Decalogue.
Just as a man has a natural love for his parents, so too
he has a natural love for his children; indeed, the
commandment of charity extends to all one’s neighbors.
But the precepts of the Decalogue are ordered toward
charity—this according to 1 Timothy 1:5, “The end of the
commandment is charity.” Therefore, just as there is a
precept having to do with one’s parents, so also there
should have been precepts having to do with one’s children
and other neighbors.
In every genus of sin it is possible to sin with one’s
heart and to sin with one’s deeds. But within certain
genera of sin, viz., in the case of theft and adultery,
sinning by deed is prohibited in one place—viz., when it
says, “You shall not commit adultery” and “You shall not
steal”—and sinning with the heart is prohibited in a
separate place—viz., when it says, “You shall not covet
your neighbor’s good” and “You shall not covet your
neighbor’s wife.” Therefore, the same thing should have
been done with the sin of homicide and the sin of false
Just as a sin can stem from a disorder of the
concupiscible [appetite], so too a sin can stem from a
disorder of the irascible [appetite]. But there are
certain precepts prohibiting disordered desire, when it
says, “Do not covet .....” Therefore, the Decalogue
should also have contained some precepts prohibiting a
disordered irascible appetite. Therefore, it does not
seem that there is an appropriate number of precepts in
But contrary to this:
Deuteronomy 4:13 says, “He showed you His covenant, which
He commanded you to do, and the ten words that He wrote in
the two tables of stone.”
As was explained above (a. 2), just as the precepts
of human law order a man toward the human community,
so the precepts of divine law order a man toward a sort
of community or republic of men under God. Now
in order for someone to live a good life in a community,
two things are required. The first is that he
behave well toward the one who presides over the community,
and the second is that the man behave well toward the
others who are his companions and co‑participants
in the community. Therefore, divine law must first
lay down some precepts ordering a man toward God and,
second, it must lay down other precepts ordering a man
toward those others who are living together with him
as his neighbors under God.
Now there are three things a man owes to the ruler of
his community: (a) fidelity, (b) reverence, and
(c) service (famulatus). Fidelity to one’s
lord consists in not conferring on someone else the
honor of preeminence; and on this score there is the
first precept, when it says, “You shall not have strange
gods.” Reverence to one’s lord requires that nothing
injurious be done to him; and on this score there is
the second precept, i.e., “You shall not take the name
of the Lord your God in vain.” Service is owed
to a lord in repayment for the benefits his subjects
receive from him; and here the relevant precept is the
third, which has to do with the sanctification of the
Sabbath in remembrance of the creation of things.
On the other hand, someone behaves well toward his neighbor
both in a specific way and in a general way:
He behaves well in a specific way to the extent that
he renders what he owes to those he is indebted to.
And on this score there is the precept that has to do
with honoring one’s parents.
He behaves well in a general way, i.e., with respect
to everyone, in that he inflicts no harm on anyone either
by his deeds or with his mouth or with his heart.
As for deeds, in some cases harm is inflicted on one’s
neighbor in his very person, i.e., with respect to his
existence as a person; and this is prohibited when it
says, “You shall not kill.” Again, in some cases
the harm is inflicted in a person joined to him in the
propagation of offspring; and this is prohibited when
it says, “You shall not commit adultery.” And
in some cases the harm is inflicted in his possessions,
which are ordered to both him and those conjoined to
him, and this is prohibited by saying, “You shall not
On the other hand, harm caused with the mouth is prohibited
when it says, “You shall not bear false witness against
And harm caused with the heart is prohibited when it
says, “You shall not covet.”
Moreover, the three precepts ordered toward God could
also be distinguished in accord with the specific differences
by deed, with the mouth, and with the
heart. The first of these three percepts has
to do with deeds, and thus it says there, “You shall
not make graven images.” The second precept has
to do with the mouth, and thus it says, “You shall not
take the name of your God in vain.” The third
precept has to do with the heart, since in the sanctification
of the Sabbath, insofar as this is a moral precept,
the stillness of the heart is directed toward God.
according to Augustine, through the first precept we
revere the unity of the First Principle, through the
second precept we revere God’s truth, and through the
third precept we revere His goodness, by which we are
sanctified and in which, as our end, we come to rest.
Reply to objection 1:
There are two possible replies to this objection.
First, the precepts of the Decalogue are traced back
to the precept of love. Now a precept had to be
given to man concerning the love of God and neighbor,
since in this regard the natural law had been obscured
because of sin. By contrast, this was not the
case with respect to the love of self, because in this
regard the natural law was still alive—or, alternatively,
because the love of self is also included in the love
of God and neighbor, since it is in ordering himself
to God that a man has genuine love for himself.
And this is why the precepts of the Decalogue contains
only precepts having to do one’s neighbor and with God.
second possible reply is that the precepts of the Decalogue
are the ones that the people received directly from
God. Hence, Deuteronomy 10:4 says, “He wrote in
the tables, according as He had written before, the
ten words, which the Lord spoke to you.” Thus,
the precepts of the Decalogue had to be such that they
could be immediately understood by the people.
Now a precept has the character of something that is
owed, and the fact that a man necessarily owes something
to God or to his neighbor is easily grasped by a man—and
especially by a man of faith (fidelis).
However, it not so readily apparent that a man is necessarily
owed something in those matters that pertain to himself
and not to another. For at first glance it seems
that everyone is free in matters that pertain to himself.
And so the precepts that prohibit a man’s disorders
with respect to himself come to the people later on
through the instruction of the wise. Hence, they
do not pertain to the Decalogue.
Reply to objection 2:
All the solemn feasts of the Old Testament were instituted
in commemoration of some divine favor, either a past
favor remembered or a future favor prefigured; and,
likewise, it was for this reason that all the sacrifices
were offered. Now among all of God’s favors, the
first and foremost is the favor of creation, which is
commemorated in the sanctification of the Sabbath.
Hence, Exodus 20:11 gives the following as the reason
for this precept: “For in six days God made heaven
and earth, etc.” Moreover, among all the future
favors that had to be prefigured, the principal and
final one was rest in the mind of God, either in the
present life through grace or in the future life through
glory. This was likewise prefigured by the Sabbath
observance. Hence, Isaiah 58:13 says, “If you
turn away your foot from the Sabbath, from doing your
own will in My holy day, and call the Sabbath delightful,
and the holy of the Lord glorious ......” For
these are the favors that are first and foremost in
the minds of men, especially men of faith.
contrast, the other solemn feasts are celebrated because
of certain particular favors that were temporally transitory.
Take, for instance, the celebration of the Passover
because of the favor of the past liberation from Egypt
and because of the future passion of Christ. These
events have passed in time, leading us into the rest
of the spiritual Sabbath. That is why, among the
precepts of the Decalogue, mention was made only of
the Sabbath, while all the other solemn feasts and sacrifices
were left out.
Reply to objection 3:
As the Apostle says in Hebrews 6:16, “Men swear by one
greater than themselves, and an oath for confirmation
is the end of all their controversy.” And so since
oaths are common to everyone, the prohibition of disordered
oaths is specifically made in a precept of the Decalogue.
contrast, the sin of false teaching is relevant only
to a few people, and hence it did not have to be mentioned
among the precepts of the Decalogue. (Still, according
to some interpretations, the precept “You shall not
take the name of your God in vain” does prohibit false
teaching; for instance, one Gloss expounds [this precept]
as follows: “You shall not claim that Christ is
Reply to objection 4:
Natural reason directly dictates to a man that he should
not inflict injury on anyone, and so the precept prohibiting
harm extends to everyone. However, natural reason
does not directly dictate that a man should do something
for another’s benefit, except in the case of someone
to whom the man is indebted. Now the debt a child
owes to his father is so obvious that it cannot be denied
by any sort of evasion. For the father is a principle
of generation and of esse and, afterwards, of
upbringing and teaching. And this is why it does
not fall under a precept of the Decalogue that support
or obedience should be given to anyone other than one’s
On the other hand,
parents do not seem to be indebted to their children
because of any favors received from them; rather, just
the opposite is the case. Likewise, as the Philosopher
puts it in Ethics 8, a child is a part of his
father, and fathers love their children as a part of
themselves. Hence, the reason why there are no
precepts in the Decalogue with regard to love of one’s
children is the same as the reason why there are likewise
no precepts that order a man toward himself.
Reply to objection 5:
The pleasure of adultery and the usefulness of riches
are desirable for their own sake, insofar as they have
the character of a pleasurable good or a useful good.
For this reason, what had to be prohibited in their
case was not just the deed, but the desire (concupiscentia)
By contrast, homicide
(homicidium) and falsehood are horrific in their
own right; for we naturally love our neighbor and love
the truth, and they are not desired for the sake of
anything else. And so as far as the sins of homicide
and false witness were concerned, it was necessary to
prohibit only the deed and not the sin of the heart.
Reply to objection 6:
As was explained above (q. 25, a. 1), all of the
irascible passions stem from the concupiscible passions.
And so in the precepts of the Decalogue, which are, as it
were, the first elements of the Law, mention had to be
made only of the concupiscible passions and not of the