Lindelof and Cuse's get out clause by Adam23

Before I get to the theory, I have to do a bit of background. Having watched the Lost finale I can't say I'm entirely disappointed nor entirely satisfied. People can say that the end revelation of the flash-sideways as a type of holding place was an answer but it only answered a question that was provided in Season 6. The fact is though that the nature of the island, the source and the smoke monster were left wholly unexplained. Agreed, there was closure (and brilliantly constructed emotional closure it has to be said) but that's not quite the same thing.

And now to the theory. What the writers have done is quite clever or cowardly depending on your point of view. By providing closure for characters but leaving the mythology of the island relatively untouched and open ended you are invited to make you own closure on the theoretical side. This implies that either the nature of the island was sussed out immediately by viewers(and the concept of flash sideways as purgatory implies that this might have been their original concept) which meant that they had to make a violent u-turn, buy time and resultantly constructed a couple of series that ran away from themselves. Or, they had always had this overall plan that it would be the fans individual overall concept of the show that mattered and they would not attempt to destroy that.

So you can trawl through the theory as much as you like in search of a definitive answer and beg the writers themselves for an answer but it won't come to fruition because the pair didn't have one, or if they did it was lost seasons ago in the expectation and accurate guesses at the time. You can take small solace in the fact that either you're granted this rare and massive freedom of expression on the show unlike most other series.

Personally, I reckon the island was some sort of Pandora's box.

But hey, what do I know?