I’ve been enjoying “Lost” since its debut, but it wasn’t until the episode that aired on 2/28/08 that I realized the show truly does have the vision its creators say it has. “The Constant” is the episode that the Lost producers/writers could not have completed if they didn’t know where they were going with the show. And “The Constant” makes the show true sf. Excellent sf. And I’m relieved that everything I was hoping they were doing is exactly what they’re doing. If you’re one of the five people in America who hasn’t been watching “Lost,” now is the time to start.