When Locke goes to visit him, Ben is reading Philip K. Dick's "VALIS", a science fiction novel where the writer becomes slowly the protagonist of the story, living it and no longer being able to take control of it.
Ben is reading the book "Varis" by Philip K. Dick (1981). The writer was quoted in an interview as explaining: "So, if you superimposed the past (ancient Rome) over the present (California in the 20th century) and superimposed the far future world, you got 'the Empire', as the supra- or trans-temporal 'constant'. Everyone who had ever lived was literally surrounded by the iron walls of the prison; they were all inside it and none of them knew it." This certainly gives a hint of the nature of the island or, perhaps, the entire series undercurrent itself.