If last episode was the one where everyone died, this is the one where lots of questions were answered. Most importantly, we learn about the origins of Jacob and the MiB (and they're way more satisfying than Richard's story):
Claudia gives birth to twins...Man in Black and Jacob are twins! Of course! How did we not see it all along? The black and white thing is really driven home in this episode, in everything from clothing to hair color.
Theory: The whole black-and-white-as-good-and-bad thing has been a ruse. Black and white instead represents the Taoist concept of yin and yang: two opposite forces (Jacob and still unnamed Brother/MiB) are seemingly opposite yet are really interconnected and complementary. We see in this episode that MiB—just like Ben and the Others, just like most other Lost "villains"—is really nuanced and quite justified in his rage and actions. If Allison Janney (playing Mother) killed my mother and lied to me about where I was from, I'd be pretty pissed too. Nice play by Lost writers after so strongly convincing us last week, with the deaths of Sun and Jin, that MiB is pure evil.
Unanswered Question: So if MiB has his reasons for being so smoketastic and vengeful, why is Widmore so evil? Where does he fit in to all of this?
Claudia, the twins' birth mother, wears Greco-Roman style clothing. She and Allison Janney speak in a Latinish language. Allison Janney kills Claudia, marking the third time we've seen a woman arrive on the island pregnant only to give birth and have her baby taken away (the others were Rousseau and Claire). Claudia only gets the chance to name Jacob and not the second baby.
Theory: There's no way a Roman ship could be in the South Pacific. When Jacob and MiB begin their time on the island, it's located somewhere in the Mediterranean or perhaps in the Atlantic near Spain. At some point during the Jacob reign, the island must have moved.
Question: Where else has the island been?
Mother shows the 13-year-old (perhaps an allusion to the age of Bar Mitzvahs, when Jewish boys become men?) twins the "Source" (which was, if you ask me, disappointingly Disneyfied), the electromagnetic or whatever light in a cave that makes the island so special. One of them, she says, will become its protector. This later ends up being Jacob, after Brother and Mother are estranged, after Mother thinks she has killed Brother. Mother tells Jacob that going into the Source is "worse than dying."
Confession: I was really disappointed with the scene when Mother shows them the Source until we later see Brother building the wheel that Ben uses to leave the island in "There's No Place Like Home" (Season 4). For some reason, that connection made the whole beautiful, glowing light cave thing seem like less of a cop out.
Theory: If going into the Source is "worse than dying" does that mean our alternative timeline isn't some type of heaven where everyone gets what they want, but actually a purgatory?
It's easy to imagine that the twins might get kinda bored growing up on the island. With only each other and Mother for company, the main activities seem to be staring out at the ocean and boar-hunting. As adults, Brother seems to take up weight-lifting (check out his guns!) while Jacob prefers weaving. And also, they play Senet, an ancient board game. During one game, Brother tells Jacob he can't make a move—it's against "the rules." One day, Brother says, Jacob can make up his own game and everyone will have to follow his rules.
Theory: We learn a bit more about "the Rules" governing guardianship of the island. Jacob and Brother can't kill each other, yet they can kill Mother, the previous guardian. This relationship with our survivor candidates is still unclear. Jack has proved that he can't kill himself. Is this true for all candidates or only the "true" candidate? Jack also recognizes that MiB can't kill the candidates, but the candidates can kill each other.
And: While Mother is protector of the Source, she is also Smoke Monster (how else would she kill Brother's entire camp?). She is the whole of which Jacob and Brother are parts.
Mother kills Brother after she finds out about his plans to leave the island. She also kills all of his people. He's not really dead, but comes back to kill her instead (she then thanks him). When Jacob sees this, he knocks Brother out and throws him into the "Source"—a fate worse than death. Smokey erupts from the cave, knocking Jacob over. Jacob later finds his Brother's body. He lays Mother and Brother to rest—flashforward to Jack and Kate finding the bodies in Season 1, Locke deeming them "our own Adam and Eve."
Props go to: Lost writers for not making Adam and Eve Jack and Kate as everyone had thought all along.
Theory: Hello, Bible allusions. This episode is an interesting inverse of the Cain and Abel story, where the "good" Abel (Jacob) ends up killing "evil" Cain (Brother). Also, the island is sort of like Eden: Brother gains knowledge, leading to his downfall, while Jacob remains in an ignorant "believing" state. However, instead of being expelled from the island, Brother is trapped there.
The "others" living on the island during Jacob's childhood (survivors of Claudia's shipwreck) are referred to by Mother as "bad people." They come to the island, fight each other, destroy, corrupt. "It's always the same," she says. When Brother goes to live with them, he concedes, telling Jacob that they are "greedy, manipulative, untrustworthy, and selfish."
Truth: This describes all people, really.
Theory: The final battle won't be simply a matter of good vs. evil. Lost is way more than that.