Lost... Back to the Future Style

In typically Lost fashion, tonight was one of those episodes that created more questions than answers. Tonight's episode focused almost solely on Desmond. We learned that the island can cause a reaction that can make people time travel on a conscious level. Desmond began freaking out because his mind kept going back and forth between 1996 and 2004. All the while Desmond was thinking it was 1996 - therefore he didn't know where he was or who Sayid was. 

We learned from Daniel Farraday that when this happens the person needs to find a constant between the present and the future or their brain will short circuit and they will die. In this case Desmond's constant was Penny. As 1996 Desmond in 2004, he talked to Daniel Farraday who told Desmond to track him down at Oxford in 1996 so he could help him. '96 Desmond tracked down '96 Michael who told him he needs a constant between his present self and future self. Desmond then tracked down Penny and told her he needs her phone number. As 2004 Desmond he knew the date was 12/24/04. In '96 he told Penny he would call her on exactly that day in 2004. After he talked to Penny, he no longer had episodes between the past and present.

The end of the episode ends with Michael looking through his journal - which now would be altered b/c he had met Desmond in 1996. He flipped open to a page that said in red: If anything goes bad, Desmond Hume will be my constant.