According to Norway's oldest written laws and Old Norwegian Homily Book, the consecration of the church was valid as long as the four corner posts were standing. One of the sermons in the old homily book is known as the "stave church sermon". The sermon dates from around 1100 and was presumably performed at consecrations, or on the anniversary of such. The sermon text is a theological interpretation of the building elements in the church. It names most of the building elements in the stave church, and can be a source of terminology and technique. For instance, the sermon says: "The four corner posts of the church are a symbol for the four gospels, because their teachings are the strongest supports within the whole of Christianity."