Leviticus, the standard English title, means "relating to the Levites", while the traditional Hebrew name for this book is Vayikra, which means "And he called". Conveniently, this is just the first word of the book.
Much of the biographical information about Leviticus is the same as Genesis and Exodus. They are written cohesively in a common structural framework, possibly even by the same author(s), in the same time period and with the same cultural background. As such, I would encourage my readers to go back and review my introduction to Genesis, because I'm not going to repeat that material here. JEDP theorists would disagree with me. They would not consider Leviticus to be a single book at all, but rather a compilation of multiple sources with a variety of editors, which makes questions like "when was Leviticus written" partially nonsensical, because in their view "Leviticus" is not a unified book. Since Leviticus is presented to the reader as a cohesive unit, that is how I will regard it for the purposes of my commentary.
Thematically, I pointed out many differences between Genesis and Exodus. Leviticus in general is much more closely aligned with Exodus than with Genesis. Both Exodus and Leviticus contain substantial legal sections ordaining parts of the Mosaic Covenant. While Exodus is substantially focused on the architecture of the Tabernacle, Leviticus is mostly (but not entirely) focused on ceremonial law, covering a range of topics like the protocol for animal sacrifice, a variety of laws governing ceremonial uncleanliness, how to diagnose and treat skin diseases and mold, the institution of an annual atonement (separate from the Passover), and the list goes on. So immediately one can see that the topics of Leviticus are very different from Exodus, and yet the broad theme is the same: establishing the rules and regulations governing the Israelite community in how they relate to each other and to God. In effect, it is really more of a continuation of Exodus than anything else.
Many of these subjects do not seem religious, like the laws governing skin diseases and mold. That's why I specifically pointed out in my commentary about Exodus that the LORD was seeking to build both a religious, legal and cultural framework for the nascent Israelite people. Of course it seems peculiar to our modern, secular sensibilities that their legal code would be religious, since the very essence of secularism is the separation of church and state. As should be immediately evident, this has not always been the case. Also remember that when I talk about the Abrahamic and Mosaic covenants as types of suzerainty lordship treaties that this language is only partially metaphorical. In many instances, especially in the Pentateuch, the LORD in fact does regard himself as the lord of the Israelites, and that gives him a lot of authority to institute exactly the sorts of legal and cultural rules that are embodied in Leviticus, as well as the religious rules that we would expect.
Even more so than Exodus, the book of Leviticus is chiefly composed of Things The LORD Said, i.e. extensive, multi-chapter monologues. In fact, this is nearly the entire book, with only a few stories mixed in to exemplify the laws that the LORD is trying to establish. As such, Leviticus is perhaps best known as "the book nobody reads". In conversations with friends, I have anecdotally observed that most people who start reading the bible from Genesis onward usually grind to a halt in Leviticus because the material is so dense and to many, so uninteresting.
In the words of one of my friends, in Genesis every chapter seems like it has a thousand years of history, while in Leviticus every year in the story seems to take a thousand chapters. I.e. Genesis has tons of events packed into every chapter, while the entire book of Leviticus is just one long speech, while the Israelites are still at Mount Horeb. (Remember when the Israelites arrived at Mount Horeb back in Ex 19? They are still there. Seriously.)
So I have something of a challenge to present this book in an interesting and engaging way. The upshot is that we can learn a lot about how ancient Israelite society functioned through these laws. Also, I might put cat pictures in my later posts. But you won't know which ones have cat pictures unless you read them, so... there's that. Everyone loves kittens, right? Yeah, this will work great...
In addition to the kittens, I think there are a couple broad points that I want my readers to look for while we go through Leviticus. The first, that I've already mentioned, is what this book implies about Israelite society. We can see through these regulations what are the common problems and social expectations that they held. Second, I want my readers to look at how the Israelites are expected to relate to God. In particular, we will see the concept of atonement in many of the rituals of this book. What was established in passing in Genesis and Exodus is firmly driven home by Leviticus: the people must atone for the sins that they have committed by sacrifice. Third, look at the roles and responsibilities of the priests. Most of this book establishes laws governing the people, but many of these laws are administered by the priests. Even in social and legal arenas, the priests have the authority to oversee the compliance of the people.
The priests were initially introduced in Exodus for the purpose of maintaining the Tabernacle and offering sacrifices, but now we can see that their role is expanding into other realms of Israelite society, in parallel with the institution of ceremonial cleanliness laws. However, their central role will always be servicing the Tabernacle, as it relates to sacrifices, atonement and all the other rituals.
With all that said, I think we are ready to move on to Leviticus 1.