Because it was important in the post-exilic period to give a new emphasis to the religious institutions that had been neglected, an attempt was made to show the very ancient origin of each of them. For example, the story of Creation culminates in the institution of the Sabbath. The Deuteronomic narrative indicates that the Sabbath is to be observed as a memorial to the Israelites' deliverance from Egypt, but in the P narrative, the reason for observing the Sabbath dates to the time of Adam and the creation of the world. The story of Noah and the Flood provides a setting for the laws that prohibit murder and the eating of blood. Circumcision, of a deep religious significance for the Hebrews, is now said to have been introduced by Abraham, and the Feast of Passover was established by Moses. Each of these religious institutions or practices was not only of ancient origin but was introduced by one of the great characters of the past.
The history of the periods covered in the J and E narratives is passed over quickly except for those particular points that needed special emphasis. The story of the march through the wilderness includes a great deal of material not found in the older narratives. This new material largely details instructions concerning the offering of sacrifices and other ritualistic performances. The reason for these in-depth instructions was the obvious desire on the part of the authors to show that the priestly requirements of the post-exilic age were really in force from the time when the Hebrews left Egypt. Although the law of the Central Sanctuary, which deals with the Temple in Jerusalem, is actually a later development, the P historians explain the ancient character of the law in their account of a moving sanctuary made according to instructions given to Moses and carried by the Hebrews as they journeyed through the wilderness. This moving sanctuary was no more than a tent, but it contained rooms and equipment that corresponded to the Temple of later years. Of the many ceremonies that are described in detail, the most important are those pertaining to the services to be performed on the Day of Atonement.
