I apologize if anyone has brought this up before...I'm not up to date on some of the recent posts. What Jacob says at the beginning of The Incident Part 1 has always puzzled me and I have a possible idea as to what he could mean. He says, "It only ends once and anything before that is just progress", replying to the man in black's statement of "it always ends the same." Now, we all were taught in the episode "Flashes Before Your Eyes" from Mrs.Hawking that the universe has a way of course-correcting itself and you cannot change the past/future from happening. She uses the example of the man falling from the scaffolding and that if she would have warned him, he would have just died from some other cause shortly after being saved from his previous fate. While some could argue that the future from that point goes on the same, I tend to disagree. We should all be aware of the butterfly effect, but for those not, it is described as "Small variations of the initial condition of a dynamical system may produce large variations in the long term behavior of the system". Or, simply put, small changes can have drastic effects after time. An example using Mrs.Hawking's scenario: The man doesn't fall off the scaffolding after being warned, but is hit by a car later that day. Let's just say that the person driving that car was a doctor who was on the way to the hospital to save someone else's life, who now dies and doesn't end up finding the cure for cancer. I know that explanation is very far-fetched and brief, but it is just to illustrate my point. Because he was warned, cancer just survived for x number of more years(until someone else figures it out) and hundreds of thousands of people die just from him living those extra hours after being forewarned. Some will say, "That wouldn't happen because the universe won't course correct that way" and they are probably right, but they are only half-right. My theory is that Jacob is talking to the Losties at these pivotal points in their lives, if only to change the most minute of things, a "little push" as he calls it to Jack. It is as if they are in this constant loop, over and over again, the losties come to the island, and every time they do, Jacob gives these little pushes, so that in the big scheme of themes, these little pushes will eventually lead to a "different ending". That by making many small changes, the future can be changed, over time. The "man in black" says it always ends the same, but that is because it takes many of these small pushes over many cycles of this time loop to finally make it end differently. That may be what Jacob means that it only end's once, and these time loops with these "pushes" are the progress. Anyways, sorry that was so long, I'm sure someone will have an easy way to disprove this, and that works fine with me...that way I can stop considering it.