THE CATECHISM OF ST. PIUS X
The Third Commandment
1 Q: What does the Third Commandment: Remember thou keep holy the Sabbath day, command us to do?
A: The Third Commandment: Remember thou keep holy the Sabbath day, commands us to honor God by acts of worship on festivals.
2 Q: What are festivals?
A: In the Old Law they were Saturdays and certain other days regarded as specially solemn by the Jews; in the New Law they are Sundays and other festivals instituted by the Church.
3 Q: Why is Sunday sanctified instead of Saturday in the New Law?
A: Sunday, which means the Lord’s Day, was substituted for Saturday, because it was on that day that our Lord rose from the dead.
4 Q: What act of worship is commanded us on festivals?
A: We are commanded to assist devoutly at the Holy Sacrifice of the Mass.
5 Q: With what other good works does a good Christian sanctify festivals?
A: A good Christian sanctifies festivals: (1) By attending Christian Doctrine, sermons, and the Divine Office; (2) By frequently and devoutly receiving the sacraments of Penance and the Blessed Eucharist; (3) By the practice of prayer and works of Christian charity.
6 Q: What does the Third Commandment forbid?
A: The Third Commandment forbids servile works and any other works that hinder the worship of God.
7 Q: What servile works are forbidden on festivals?
A: The servile works forbidden on festivals are those works called manual, that is, those material works in which the body has more part than the mind, such, for instance, as are ordinarily done by servants, laborers, and artisans.
8 Q: What sin does one commit by working on festivals?
A: One commits a mortal sin by working on festivals; brevity of time, however, will excuse from grave sin.
9 Q: Is no servile work at all permitted on festivals?
A: On festivals those works are permitted which are necessary for life, or for the service of God; as well as those done for a grave reason, with leave, when possible, from the Pastor.
10 Q: Why is servile work forbidden on festivals?
A: Servile work is forbidden on festivals in order that we may the better attend to divine worship, and to the care of our souls; And to enable us to rest from toil. Hence innocent recreation is not forbidden.
11 Q: What else above all should we avoid on festivals?
A: We should above all avoid sin and whatever leads to sin, such as dangerous diversions and dangerous places of amusement.