[ator]

"the island needs you, you have to go back before it's too late"

This is what Kate hears on the phone in her dream when the scene is run in reverse. Now some say it is Locke, but taking into account the time of the call, i.e. 3 years later, are we to assume that for the first few years nothing bad happens on the island, but then Locke tells Jack that after he left 'bad things happened'. This doesn't mean straight away, many years could of passed before something happens on the island. But it would seem that the island needs them all to come back, and without knowing it Jack is drawn back to it, and tries to get Kate to come with him. Ben hints that he knows something, when he tells Jack that all of them have to go back at the same time. I believe that the island needs certain people or an X amount of people on the island. What do you think?