thumb|500px|rightWe all picture "The Constant" as inspiring the flash sideways awakenings - a character contacts something of great significance to anchor themselves and cure their amnesia. But we shouldn't forget Claire, who was waking up to memory flashes back in Season 2.
Libby's early amnesia definition clues us in on what happens when we die: "Sometimes when something terrible happens to us there's a little switch in your head that flicks on to protect us from having to deal with it. Maybe your memories aren't gone. Maybe you're just blocking them."
And what could be more terrible than dying? Yet characters can deal with that as well. But no one does it alone, Jack.
So add "Claire's amnesia" to our list of things of iffy concepts that seem better if we imagine they foreshadow season 6. Other items on the list - the Swan timer's hieroglyphics, recreating the original Oceanic flight, Locke's "Tabula Rasa" stare...