MIB is visited by Jacob, shows him magnetism at a well, tells him people are bad

When we return for Act 4 of the episode, we jump forward 30 years and we see Jacob as an adult at the caves working on a tapestry. Mother sits close by pressing something in a mortar with a pestle. She seems distant as Jacob turns to her and asks her what she thinks of his tapestry. She says that it's nice, and when he asks is she is alright, she says she's just tired.

It then cuts to a work site on another part of the island, where the other people are working on a well including the Man In Black (this is the same well that Locke fell down in season 5 to leave the island that is near the future sight of the Orchid Station). Jacob watches the site from a distance and Man In Black sees him.

Later, after the workers have gone, Jacob and MIB sit nearby playing the same Senet game from their teenage years. As the play, MIB asks Jacob if Mother knows that he visits him, and Jacob says that she never asks about him. MIB bitterly says that he's sorry he asked about her then.

He then asks Jacob why he watches his people and Jacob says that he wants to see if Mother was right about them being bad. MIB says that Mother may be insane, but she was right about the people being bad. Jacob says that they seem fine, but MIB says that's easy to say when you just watch them from a distance. He adds that after 30 years of living among them, he's learned that they are "greedy, manipulative, untrustworthy and selfish."

Jacob asks why he's with them then and MIB says they are means for him to get off of the island and they've found a way. Jacob says that is impossible because there's no way off of the island.

MIB pulls the dagger from his belt (the same one MIB gave Richard and Dogen gave Sayid) and throws it at towards the well. The dagger curves and sticks to side of the well. Jacob goes to the well and pulls the dagger from it. MIB tells him that there are smart men among his people who are curious about how thing work. He says that they have found sites all over the island where metal acts strangely and when they find these sites, they dig. He says at this site, they found something and asks Jacob to come with him.

MIB asks Jacob what he's going to do when Mother dies, and Jacob says she'll never die. MIB says that everything dies. Jacob emotionally says that he doesn't want to leave the island because it is his home. MIB replies "Well, it’s not mine."

Like so many scenes in this episode, this one is quite heavy. We see and hear about the digging of the wells, which Locke told Desmond about before pushing him down one. We see debate start about all men being bad and corruptible versus them having the potential for good (MIB's position versus Jacob's). There's certainly a lot to download and absorb.

It also seems that Mother may know that something bad is coming by the way she's acting at the caves. It's not likely that we'll ever know the full extent of the powers and abilities that the island's protectors have.