I've just been thinking about the series as a whole, and I've realized that everything that's happened lately was foreshadowed clearly in the first half of the show. Jacob, the Man in Black, the looming apocalypse, the candidates, the "game", the source, the fail-safe, all of it was talked about very early on. Sometimes without me even realizing it.
The conflict between Jacob and Esau (It seems he won't be named, so that name works) was made clear in the pilot as many already know. When Locke explained Backgammon, he said there were two sides, one light, and one dark. Jacob is light, Esau is dark. Locke also explained that the game was older than Jesus Christ, as the conflict between light and dark seems to be. This explanation of the world around the survivors as a game of light and dark/good and evil ties in with Jacob and Esau's game of Senet in the ancient past. Both of these games are merely representations of the real game between the brothers. Locke later appeared to Claire as an apparition with one white eye and one black eye, reflecting his moral ambiguity and the clash of ideologies.
It is my belief that the Man in Black didn't just turn into Locke to freak out the survivors, I believe Locke became the Man in Black in the same manner that Jack has now become Jacob and that Esau became the monster. This firmly establishes the conflict between Jack and Locke as another level of the battle between Jacob and Esau. I think Esau and Jack are very alike, and Jacob and Locke are very alike, but just like how two similar people can be enemies and two completely different people can be the best of friends, they represented their opposites. Thus why Jack, when in the role of Jacob, no longer wishes to leave the island and believes in destiny, while Locke, in the role of the Man in Black, wants to get home and believes nothing is significant.
Locke originally expressed a belief that the island was special and that they'd all been brought there for a reason. He was right about this, as he was about many things. All of those brought to the island were there for a reason, particularly the candidates. It seems Locke understood this when he saw the "eye of the island". The source. The events in the Swan are particularly interesting when looked at from a cosmic perspective. Jack argues with Desmond that maybe the button, the numbers, the quarantine, and the end of the world are all just part of some big game. Desmond admits that he's wondered this every day. In a way, Jack was right. The hatch was only where it was because Jacob had brought the Dharma Initiative to the Island. Jack and Desmond were only there because Jacob brought them to the Island. All of these events were part of a game. The best bit is Desmond turning the fail-safe key and destroying the hatch, as now he may have to activate the ultimate fail-safe and destroy the island.
In Season 3, Jack calls for rescue, Locke tries to stop him, and Ben warns him doing so will be the beginning of the end. In the same way, Locke now wants off the island, Jack is trying to stop him, and his leaving will be the beginning of the end.
Has anyone else noticed any parallels between the events of early episodes and the final events of the series?