In his Large Catechism, Luther begins by defining "holy day" and by explaining how by Christ's time the true understanding of the Sabbath had been corrupted. Because the Third Commandment describes Jewish practice int eh Old Testament, Luther plainly states that the external form of this law does not apply to Christians in the New Testament. It is an error to say that Sunday is the New Testament Sabbath. However, the internal form of this command still applies to Christians today. Christians should regularly devote themselves to a day when they can hear and learn God's Word, so that they do not despise it. For this reason Luther commends worship on Sunday for the sake of good order. In this sense, every day for the Christian should be a "holy day" consecrated by God's Word. Luther presents a clever play on words when he suggests there is only one "holy thing." The German word for "holy things" (Heiligtum) was often used to refer to relics, items believed to have belonged to the apostles and other saints. Yet Luther says the only true "holy thing" is God's Word, which consecrates all things and apart from which nothing we do or say is holy.