Goodwyn gave us a clue when he said weren't good. i this is a definite clue and goes to show why they take the innocent children. But what for? Why are they doing it?

i think it is important that we know everyone has a past. It seems everyone has to get over something and who has so far? Well, Shannon andBoone. Boone finally helped or became a leader by going to the airplane and the island took him. Shannon finally got past her life long doom of no one believing in her because Sayid did. Perhaps when you overcome your past you become free. The others took the ones without problems and once the rest overcome they die or get kidnapped.

I think this is what the island is all about: bringing these speciifc people to a place to fix their problems, like a huge psych ward. But they must make it real as possible so they go to great lengths with extras.