The Force has always been the most mysterious aspect of the Star Wars franchise, and the latest film only posed more questions than answers as Rey explored the ancient island on Ahch-To.
But while the Jedi dwelled in the village above, the darkness stayed buried below the island, leaving writer and director Rian Johnson with some explaining to do.
Warning: Spoilers for Star Wars: The Last Jedi below.
In the film, Rey begins a guided meditation with Luke Skywalker that allows her to explore the balance of the Force on the island. She is soon called to a dark hole in the ground, which Luke warns her to avoid, but she doesn't listen. As she approaches, the ground on which she sits begins cracking, frightening the exiled Jedi Master.
Johnson spoke with SlashFilm about the subject, revealing some key details about the nature of the cave and what it means to the film.
"Well, the idea that this natural place reflected," began Johnson. "The idea that if there's a Jedi Temple up top, the light, it has to be balanced by a place of great darkness. We're drawing a very obvious connection to Luke's training and to Dagobah here, obviously.
She later takes a journey to the hole, eager to see with her own eyes. It quickly sucks Rey down, casting her into a small pool of water. When she climbs out, she has a vision similar to Luke's in The Empire Strikes Back, during which she attempts to learn the identity of her parents.
"And so the idea was if the up top is the light, down underneath is the darkness," Johnson explained. "And she descends down into there and has to see, just like Luke did in the cave, her greatest fear. And her greatest fear is [that], in the search for identity, she has nobody but herself to rely on."
In that moment, Rey is faced with a vision similar to Luke's. When asking who her parents are, she is faced with a reflection of herself, foreshadowing the revelation that Kylo Ren provides later in the film.
It's a deft touch that harkens back to a key Star Wars moment, but pushes the sequel trilogy's narrative forward in an intriguing way.
It's unclear if viewers will venture back to Ahch-To in a future film, but they can see it presently in Star Wars: The Last Jedi, now playing in theaters.