345. Q. What is the second Commandment?
      A. The second Commandment is: Thou shalt not take the name of the Lord thy God in vain.

346. Q. What are we commanded by the second Commandment?
      A. We are commanded by the second Commandment to speak with reverence of God and of the saints, and of all holy things, and to keep our lawful oaths and vows.

347. Q. What is an oath?
      A. An oath is the calling upon God to witness the truth of what we say.

348. Q. When may we take an oath?
      A. We may take an oath when it is ordered by lawful authority or required for God's honor or for our own or our neighbor's good.

349. Q. What is necessary to make an oath lawful?
      A. To make an oath lawful it is necessary that what we swear to, be true, and that there be a sufficient cause for taking an oath.

350. Q. What is a vow?
      A. A vow is a deliberate promise made to God to do something that is pleasing to Him.

351. Q. Is it a sin not to fulfill our vows?
      A. Not to fulfill our vows is a sin, mortal or venial, according to the nature of the vow and the intention we had in making it.

352. Q. What is forbidden by the second Commandment?
      A. The second Commandment forbids all false, rash, unjust, and unnecessary oaths, blasphemy, cursing, and profane words.

353. Q. What is the third Commandment?
      A. The third Commandment is: Remember thou keep holy the Sabbath day.

354. Q. What are we commanded by the third Commandment?
      A. By the third Commandment we are commanded to keep holy the Lord's day and the holydays of obligation, on which we are to give our time to the service and worship of God.

355. Q. How are we to worship God on Sundays and holydays of obligation?
      A. We are to worship God on Sundays and holydays of obligation by hearing Mass, by prayer, and by other good works.

356. Q. Are the Sabbath day and the Sunday the same?
      A. The Sabbath day and the Sunday are not the same. The Sabbath is the seventh day of the week, and is the day which was kept holy in the Old Law; the Sunday is the first day of the week, and is tile day which is kept holy in the New Law.

357. Q. Why does the Church command us to keep the Sunday holy instead of the Sabbath?
      A. The Church commands us to keep the Sunday holy instead of the Sabbath because on Sunday Christ rose from the dead, and on Sunday He sent the Holy Ghost upon the Apostles.

358. Q. What is forbidden by the third Commandment?
      A. The third Commandment forbids all unnecessary servile work and whatever else may hinder the due observance of the Lord's day.

359. Q. What are servile works?
      A. Servile works are those which require labor rather of body than of mind.

360. Q. Are servile works on Sunday ever lawful?
      A. Servile works are lawful on Sunday when the honor of God, the good of our neighbor, or necessity requires them.