Just ironing out my theory I've been hammerin out for a while. Has to do with Locke in season one seeing the monster and describing it on dif occasions as "the Eye of the island" "Beautiful" "White Light"....So I'm thinking, if the Facob is the black smoke, then possibly Jacob was Lockes Light/Eye. If i continue this train of thought with my feeble pea brain.....Who could have been in the cabin, possibly trapped there, surrounded by the ring of dust/ash. I'm thinking possibly Jacob and Facob are brothers and the maybe, just maybe, there is a 3rd power on the island that they both imprisoned...perhaps thier father? Still many wrinkles and holes in this one, but i love trying to fathom my most favorite show of all time. Please share your thoughts!!!!