The Catechism of St. Thomas Aquinas

SUMMARY OF THE TEN COMMANDMENTS

These are the ten precepts to which Our Lord referred when He said: "If thou wilt enter into life, keep the commandments" (Matt., xix. 17). There are two main principles of all the Commandments, namely, love of God and love of neighbor. The man that loves God must necessarily do three things: (1) he must have no other God. And in support of this is the Commandment: "Thou shalt not have strange gods"; (2) he must give God all honor. And so it is commanded: "Thou shalt not take the name of God in vain"; (3) he must freely take his rest in God. Hence: "Remember that thou keep holy the Sabbath day."

But to love God worthily, one must first of all love one's neighbor. And so: "Honor thy father and mother." Then, one must avoid doing harm to one's neighbor in act. "Thou shalt not kill" refers to our neighbor's person; "Thou shalt not commit adultery" refers to the person united in marriage to our neighbor; "Thou shalt not steal" refers to our neighbor's external goods. We must also avoid injury to our neighbor both by word, "Thou shalt not bear false witness," and by thought, "Thou shalt not covet thy neighbor's goods" and "Thou shalt not covet thy neighbor's wife."

(For "Questions for Discussion" see Chapter.)