Time is the Essence by Cerberus108

If anyone's read my theories this might be overkill. However I don't see anyone else with this idea, and I think it's a legitimate explanation of everything we've seen on Lost. People are complaining about the light and Across the Sea, and I agree it wasn't the best episode ever. But, it wasn't a complete destruction of the show. If you thought Mother was going to say "That Light is electromagnetism!" to two little boys, you expect an abundance of answers despite the storytelling. Of if you thought "That Light is Jesus!" then you should probably go back and rewatch all of Lost, because you fell for the religious parallelisms. This show isn't about God, it never was, and it's not going to scientifically explain every little detail. It will end pretty damn awesome, and probably leave us with enough of a plothole that I'll be able to re-post this theory again (lol). So that being said, here's my theory on what the island/light/smokey/jacob all means.

We as humans want a plausible answer because we can only wrap our minds around concepts like God and facts. The one thing we can NEVER wrap our minds around is the essence of Time, and that is exactly what this show is using to trick us. From time traveling to agelessness to teleportation, this show has shown us some pretty crazy stuff. This can all be explained by realizing that this Light, the Source, is EVERYTHING we think it is. It is ultimate good, it is the fountain of youth, it is a giant pocket of exotic matter and electromagnetism. All this means it is something very special, something humans continuously try to rename and explain, but cannot. That is because this Light on the island is the origin of Time itself.

We have no clue what makes Time possible. We can't even explain the concept of Time to ourselves, because we know there is a past and future but we are always in the present. All this has to come from somewhere, and that is the Island. Throughout all of time and its multiple universes and choices we can make, the Island is always there. It is Time's Constant. Simply being exposed to this source of Time allows for some very odd powers. It can make you unstuck in time, thus experiencing flashes of the future or shifting consciousnesses. You can become nearly immortal and never age. You can also turn into a giant pillar of black smoke if you come into contact with it.

The smoke monster is a representation of what happens when a human consciousness taints the source of Time. Smokey is, in short, symbolic of the Past. He imitates people who have died and have no future. He believes humans are destined to repeat the same mistakes over and over. He feeds off our insecurities and fears created from these mistakes in our past.

This would make Jacob the future, though not in such an extreme as Smokey. Jacob is the protector of the future, of Time itself- the Source. He believes there's hope, that people can make choices, that they have a future to look forward to. He sits back and lets humans decide for themselves, to shape their own lives, as per his philosophy. He can never age because his mindset is based off this, and the attributes given to him by Time's various powers are attracted to his own ideals. Smokey's negative view rendered him a monster of the Past. Jacob's positive and untainted view allowed him to gain powers of the future. Desmond, his last words being a confession of love for Penny before he turned the failsafe, was likewise 'pure of heart' and mind. This is what gave him his special powers; the Island sensed he was more sided with the future, and thus he could see the future.

Mind you, the Island is not leaning to one side or the other. It is impassive, all of Time existing there at once. It is up to us humans to decide what power wins- the Past, which wants to swallow us all up and keep us in eternal dark, or the Future, which offers us the light of hope for another day. This is the entirety of Lost- a battle for time itself. The world will end if all goes wrong, but not just our world. Every world will cease to exist, because the Future will wink out of existence if Smokey escapes.

You can say what you want about this theory, but this transcends all the basic notions of religion and science, of God and plausible explanations. While it provides enough information to make sense, I can't begin to tell you why the Island exists or why Time originates from a single place. The thing is, this is a STORY, and the writers have their own mythology for the show, which is a mixture of many other religions and cultures. This reflects how humans all their lives try to answer what this Light is, without accepting that it is simply the key to our entire existence. It is Time, and if we did not have that, none of this would be possible.

Some quotes to back me up...
"Time is not of the essence- it IS the essence." -Pierre Chang
"But I want to keep playing the piano. I can do both. I can make time." -Daniel Faraday
"I bring people to this Island, and when they get here... their past doesn't matter." -Jacob