Ash circles are used as a measure of defence against and imprisonment of the Man in Black. Together with the DHARMA Initiative's sonar fence, this is one of the only known methods to keep the Monster at bay. Several ash circles have been seen on the Island.
An ash circle surrounded the cabin that allegedly belonged to Jacob. When Ben encountered it, he was careful to step over it without disturbing it. Inside, Ben pretended the person he believed to be Jacob was there. ("The Man Behind the Curtain") ("The Incident, Part 1") Later, when Hurley encountered the cabin, he did not see the ash circle. When he looked inside, he saw Christian Shephard and a face similar to the man Ben said was Jacob, which suddenly appeared at the window. ("The Beginning of the End") Shortly afterwards, Locke found the circle, but the cabin was missing. ("The Economist") When Locke, Ben, and Hurley trekked to the cabin for new orders, they did not appear to find the ash circle. Inside, Locke met Christian, who said he would speak on Jacob's behalf. ("Cabin Fever") When Ilana, Bram, Frank, and the rest of their party found the cabin, Bram noticed the ash circle was broken in one spot. This alarmed both Bram and Ilana, who exercised caution as she entered the cabin and found no one inside. ("The Incident, Part 1")
At the Temple, Hurley revealed to Dogen and Lennon that Jacob was dead. This alarmed them, and the Others began precautions, sounding alarms, launching a flare into the sky, and sprinkling ash circles around the courtyard. When asked why they were doing this, Lennon said it was to keep "him" out. ("LA X, Part 1")
Inside the statue
Ilana, Bram, Frank, and their group arrived at the remains of the statue of Tawaret with the body of John Locke, which they showed to Richard. After several delays, Bram became impatient and forcibly entered the statue with three men and Ben. Inside, the Man in Black (in the form of Locke) revealed Jacob was dead. This prompted Bram's men to shoot at him; he then transformed into his smoke form and attacked. While his men were being killed, Bram produced a pouch of ash and sprinkled some in a circle around himself. The Monster was unable to touch him in this circle, but it instead brought a chunk of the ceiling down, knocking Bram outside of the circle where he could be be killed. ("LA X, Part 1")
- It is said in folklore that Evil Spirits cannot harm you whilst you are inside a circle. It is likely this is where the Lost writers took the idea from.
- For fan theories about these unanswered questions, see: Ash circles/Theories
- Who created the circle around Jacob's cabin?
- Who broke the circle, and when?
- How is Dogen connected to the ash?