Other guesses Spoiler: what is the Island? Ran the 4 letters, with no "e" or "a" through a online word program. came back with thousands of words, but only a few could possibly make sense (as far as I can figure). Here they are: Brig - The Island is a prison (not sure why or for who, or why the rest of the world would depend on it? Unless it is keeping someone very dangerous confined (ie. Satan) Womb - The Island is like Eden. The birth place of all humanity and the source of our continued growth. Ties in with the Egyptian statute of fertility. Kind of metaphysical, but could be the answer. No children being born on the island is a sign that something is very wrong on the isalnd and with the world. Crib - Kind of like Womb. A place to nurture humanity. Locke built Claire a crib way back in season one. Also ties in with the no babies, interest in children, etc... Door - The Island acts as a doorway to all other possible realities. Someone has to prevent it from being opened or all the realities will mix together and chaos will happen. Ties in with the alternate reality we are seeing this season. The MIB could be from another place and by opening the door he will "escape", Jacob has to keep the door locked. This is almost the exact same plot as Season 5 of Buffy the Vampire Slayer, where Dawn was the Key to open the door between worlds. Lock - Ties in with Door above. All the same stuff applies. Ship & Plug were mentioned above. Plug would be the same thing as a Lock.