The name "Leviticus" was bestowed on the third book of the Pentateuch by the ancient Greek translators because a good part of this book consists of sacrificial and other ritual laws prescribed for the priests of the tribe of Levi.
Continuing the legislation given by God to Moses at Mount Sinai, Leviticus is almost entirely legislative in character; the rare narrative portions are subordinate to the main legislative theme. Generally speaking, the laws contained in this book serve to teach the Israelites that they should always keep themselves in a state of legal purity, or external sanctity, as a sign of their intimate union with the Lord. Accordingly, the central idea of Leviticus is contained in its oft-repeated injunction: "You shall be holy, because I, the LORD, am holy."
The main divisions of Leviticus are:
I. Ritual of Sacrifices (Lev 1-7)
II. Ceremony of Ordination (Lev 8-10)
III. Laws regarding Legal Purity (Lev 11-16)
IV. Code of Legal Holiness (Lev 17-26)
V. Redemption of Offerings (Lev 27)