The Cabin with the circle of ash surrounding it always seemed to me to be a prison of sorts, what if it was to be the prison for Esau?
Here is my theory: The Captain of the Black Rock, comes to the island and does what Esau said they would do, he builds himself a cabin, someone sets fire to the cabin killing the Captain, Richard maybe? With the dead Captain in the cabin Jacob binds Esau to the cabin, hence the ring of ash, that is why he can take the guise of the Captain, who is the Man in the Cabin, along with other dead persons.
Many years later, Locke has a drug enduced dream/vision of Horace chopping wood to build himself a cabin for him and the misses, a ploy by Esau to get Locke to come to the cabin here his plea, and thus become his pawn.
So one little Cabin built by a marooned Slaver Captain has so much to do with the future of the island of the sides of good and evil.