PORTALS

 A "portal" is a doorway, gate, or other entrance, esp. a large and elaborate one. It also means in computer science, an Internet site providing access or links to other sites. As an adjective, portal means of or relating to an opening in an organ through which major blood vessels pass, esp. the transverse fissure of the liver.

There were many heated debates during the original series about whether the island itself was some form a portal to another world, universe, or dimension. The portal idea made sense to some because of the bizarre unexplained components of the early series story construction. Further adding to the mysteries were the hieroglyphs in the FDW that indicated that there were several "gates" that the wheel moved to including "Earth gates."

When the concept of the "light force" which was described as "life, death and rebirth" was introduced as the catalyst to get to the End in Season 6, it added another level of evidence that the island sat on something more than volcanic rock.

A cross section from the clues results in the above diagram. The snow globe effect described by Desmond and confirmed by the difficulty of finding the island despite all modern technology shows the unique metaphysical properties of the island energy field. The light source was found in various wells or caves by islanders, who tried to tap it in order to escape the island's hold. Using the force by turning the FDW resulted in people being transported through both time and space. A disruption of the light force (the Incident) resulted in the island world (or some of the souls on the island) to violently time skip and nose bleed as their brains turned to mush. The events on the island were at least in part psychically connected to the souls trapped in a state of limbo in the sideways world.

If you look at the shape of the diagram, it occurs to me that it looks partly human. The snow globe is the human skull, as it protects and shields the brain from danger. The island could be the memory banks of the brain, its experiences and connections. The underground could be the subconscious where a person's dreams, fears, secrets and nightmares reside. The portal may be the engine or the heart of the person. In ancient Egyptian death rituals, a person's heart would be weighed against a feather to determine if the person was worthy of an after life. And the sideways represents the person's internal soul which remains hidden during life from the mind and subconscious but to be awakened in the after life.

The island construction could be symbolic of various beliefs in the after life transit of a person's soul (the collective personality, memories, accomplishments, sins, connections, and bonds) needed to move forward into another realm of existence.