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Life, death, rebirth. It’s the source, the heart of the Island…

Mother, "Across the Sea"

The Heart of the Island, also known as the Source, is the electromagnetic core of the Island. The energy radiates out from here to other parts of the island, notably in a much smaller quantities than those that exist at its source. The electromagnetism exists at the Heart in its strongest form, one that, if tampered with, had the potential to destroy the Island, and quite possibly, the entire world.

The Heart is located just beyond the bamboo grove where Jack first found himself after the crash of Oceanic Flight 815. ("Pilot, Part 1") From the outside is appears as a glowing yellow light emanating from a tunnel into which a river flows, ending in a waterfall that drops into the tunnel. The light is considered "beautiful", "the warmest, brightest light you've ever felt". However, to enter the light is forbidden, and is said to cause a fate "worse than death". ("Across the Sea")

Inside the tunnel, at the bottom of the waterfall, lies a volcanic cave with a pool in the center, plugged by a rock that glows brightly. There are extreme levels of electromagnetism in the cave, higher than any other location on the Island. ("The End")

Mother thought the Heart of the Island to be a physical manifestation of "life, death, [and] rebirth". Humans supposedly covet the Heart because a portion of the light is inside every living thing —"but they always want more". According to Mother, while humans are incapable of taking the light, their attempts to do so could "put it out. And if the light goes out here... it goes out everywhere." ("Across the Sea")


The Man in Black is thrown into the Heart

As it turned out, the Island sat on an enormous pocket of electromagnetic energy. This energy originated from the center of the Island, the Heart, and was the source of all the electromagnetism on other parts of the island. ("What They Died For") Deep inside the heart were several ancient water ducts, located all around the cork and the pool. These ducts carried the combination of water and electromagnetic energy, known to have healing properties, to other parts of the Island, including possibly, the Temple, explaining the Healing Spring. ("LA X, Part 1") The cork contained the energy and kept it at bay. As Mother explained, men covet the light, and if they were to seek it, it would go out. This was shown to be quite literal, as when Desmond removed the cork, the energy was released and caused the Island to literally collapse. Had Jack not plugged the cork back into place, the situation would have escalated, sinking the entire Island, and possibly having global implications, similar to the similar incident in the Swan and the button that "saved the world."


The early history of the heart is unknown, but the inside chamber was not made by natural processes, and Mesopotamian cuneiform script is visible on the stone plug in the center of the pool.

Jack and The Man in Black look down the the cave to the Heart of the Island

Several millennia before the crash of Flight 815, Mother was the protector of the Heart. She lived on the Island with two children, Jacob and the Man in Black. Sometime, when Jacob and the Man in Black were thirteen, Mother walked them blindfolded to the cave, where she showed them the light. After Jacob's brother left him and Mother, he searched for the Heart for 30 years unsuccessfully, but eventually he discovered that the light could be accessed underground in spots where there is strong magnetic activity.
6x15 TheHeartOfTheIsland

Mother shows Jacob and the Man in Black "The Heart of the Island."

When Mother learned of this fact, she made Jacob the new protector of the Heart. After the Man in Black killed Mother, Jacob threw him into the light, and a roaring pillar of black smoke came shooting out of the cave. Jacob later found the dead body of his brother on a crop of rocks near a river, and laid the body to rest in the caves next to his mother. ("Across the Sea")

Jacob spent many centuries as the protector of the heart. During this time, the Man in Black tried to kill Jacob and leave the Island. Jacob was murdered by Ben in 2007, and the Man in Black then set out on a mission to destroy the Island and extinguish the Heart. Jacob appeared to his candidates and made Jack the new protector of the heart.

After accepting Jacob's position, Jack was told that the Heart of the Island was located past the bamboo forest where he first woke up. Jacob told Jack that though he may have been unable to find it at first, he would now be able to. Jacob claimed that it was at the center of the Island. ("What They Died For")

Desmond sees the source of the electromagnetism and the water ducts deep within the Heart of the Island

When Jack met with the Man in Black, they joined up to have Desmond enter the Heart of the Island and put the light out. The Man in Black wanted to extinguish the light permanently to sink the Island, and Jack wanted to put it out temporarily so he could kill the Man in Black. The three of them entered the cave and lowered Desmond down with a rope. When he reached the bottom, Desmond found an ancient cave structure, and a brightly glowing rock acting as a cork in a pool of radiant light. As he approached the rock, he was bombarded with electromagnetism, and passed out once he'd managed to remove the rock. The light began flashing brightly, and a series of hissing and crackling noises issued from the ground as Desmond pulled the stone out of the hole. The water drained out of the pool, and the water flowing from the pipes stopped. Heat, steam and a dark red light began issuing from the hole as the Island began to crumble into the ocean.

Desmond removes the cork from the Heart of the Island.

It was found that after putting the light out, the Man in Black was mortal. After he was killed, Jack returned to the Heart with Ben and Hurley. There, Jack, knowing that his task to reactivate the Light and rescue Desmond was a suicide mission, named Hurley as the Island's new protector.

Ben and Hurley lowered Jack into the cave, where he woke Desmond, tied the rope around him, and put the stone back into the hole. This caused the water to start running again and he placed his hand on a stream as he collapsed near the edge of the pool. The water that he touched reached the stone, and the light was reignited, saving the Island. ("The End")

Notable visitors

Picture Name First visit Last visit Reason for Visit
Mother "Across the Sea" "Across the Sea" Earliest known protector of the Heart. Brought Jacob and The Man in Black as children to The Heart in order to inform them of their condition of candidates. He later brought Jacob back, making him protector of the island.
Jacob "Across the Sea" "Across the Sea" Was brought to the Heart by Mother as a child, where he learned he was a candidate to succeed her as as protector of the island. He later returned, and accepted the job. His successor was Jack.
Man in Black "Across the Sea" "The End" Was brought to The Heart by Mother as a child to learn of his candidacy to become its protector. After he killed Mother, Jacob knocked him out and throws him down the stream into The Heart. After a moment, the Man in Black burst forth from the Heart as the Smoke Monster. Later, Jacob found his brother's original body downstream from the Heart. The Man in Black returned in the form of Locke with Jack and Desmond with the goal of "putting out" the light and destroying the island. He became human soon after the light went out, and was killed by Jack and Kate.
Hurley "The End" "The End" Followed Jack after refusing to leave the island. There, he becomes its new protector, rescues Desmond, and hires Ben as his advisor.
Desmond "The End" "The End" Was brought to The Heart by Jack and the Man in Black. He entered the cave, and after putting out the light, he passed out. He was later rescued by Jack, who tied the rope around him, and was carried out by Hurley and Ben.
Jack "The End" "The End" As protector of the island, he visited The Heart with the Man in Black and Desmond to carry out his plan to kill the former. After achieving success, he returned to name Hurley as his successor as well as to reignite the light. He later died from injuries sustained from his fight with MIB.
Ben "The End" "The End" Followed Jack and Hurley to The Heart after refusing to leave the island. Comforts Hurley after Jack's death and accepts his offer to become his advisor, therefore gaining the role he always wanted from Jacob.

Unanswered questions

Unanswered questions
  1. Do not answer the questions here.
  2. Keep the questions open-ended and neutral: do not suggest an answer.
For fan theories about these unanswered questions, see: The Heart of the Island/Theories
  • Whose skeletons are near the Heart?
  • Who built the masonry around the Heart, and how?
  • Where do the four tunnels that drain water from the Heart go?
  • Why did exposure to the Heart turn the Man in Black into the Smoke Monster, but do nothing to Jack?
  • Why does removing the stone plug stop water flowing into the pool?

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