Obj. 4:  Further, just as man has a natural affection for his parents, so has he also for his children.  Moreover the commandment of charity extends to all our neighbors.  Now the precepts of the decalogue are ordained unto charity, according to 1 Tim. 1:5:  “The end of the commandment is charity.”  Therefore as there is a precept referring to parents, so should there have been some precepts referring to children and other neighbors.

Obj. 5:  Further, in every kind of sin, it is possible to sin in thought or in deed.  But in some kinds of sin, namely in theft and adultery, the prohibition of sins of deed, when it is said, “Thou shalt not commit adultery, Thou shalt not steal,” is distinct from the prohibition of the sin of thought, when it is said, “Thou shalt not covet thy neighbor’s goods,” and, “Thou shalt not covet thy neighbor’s wife.”  Therefore the same should have been done in regard to the sins of homicide and false witness.

Obj. 6:  Further, just as sin happens through disorder of the concupiscible faculty, so does it arise through disorder of the irascible part.  But some precepts forbid inordinate concupiscence, when it is said, “Thou shalt not covet.”  Therefore the decalogue should have included some precepts forbidding the disorders of the irascible faculty.  Therefore it seems that the ten precepts of the decalogue are unfittingly enumerated.

On the contrary, It is written (Deut. 4:13):  “He shewed you His covenant, which He commanded you to do, and the ten words that He wrote in two tablets of stone.”

I answer that, As stated above (A. 2), just as the precepts of human law direct man in his relations to the human community, so the precepts of the Divine law direct man in his relations to a community or commonwealth of men under God.  Now in order that any man may dwell aright in a community, two things are required:  the first is that he behave well to the head of the community; the other is that he behave well to those who are his fellows and partners in the community.  It is therefore necessary that the Divine law should contain in the first place precepts ordering man in his relations to God; and in the second place, other precepts ordering man in his relations to other men who are his neighbors and live with him under God.

Now man owes three things to the head of the community:  first, fidelity; secondly, reverence; thirdly, service.  Fidelity to his master consists in his not giving sovereign honor to another:  and this is the sense of the first commandment, in the words “Thou shalt not have strange gods.”  Reverence to his master requires that he should do nothing injurious to him:  and this is conveyed by the second commandment, “Thou shalt not take the name of the Lord thy God in vain.”  Service is due to the master in return for the benefits which his subjects receive from him:  and to this belongs the third commandment of the sanctification of the Sabbath in memory of the creation of all things.