LOST is an amazing show.
This is my favorite episode of LOST and I eagerly await the day where another episode takes its place. I refer to it as my favorite episode because it is perfect in every sense. The flashbacks are flawless, there are some hilarious scenes, tons of shocking parts, the writing is amazing, and it moves the plot forward immensely. In my opinion, the flashbacks in this episode are the best of the series, so far. They tell of the time Locke spent with his father immediately after he finds him. Locke was a clerk at a toy store when, one day, his mother came to the store and told him who she was. After this, Locke goes on a search for his father by hiring a private investigator. Things go up from here but, in the end, we realize that Locke's father has conned him. He had acted like he loved him until Locke offered to give Anthony his kidney which is exactly what he was waiting for. After that, he dropped back Locke into the world and wanted nothing to do with him. In the words of Anthony Cooper, Locke was "not wanted." Like every Locke flashback, the story is heart-wrenching and beautifully written.
Nevertheless, the flashbacks are not the main focus of this episode. On the island, Locke and Boone try and try to get the hatch open--they even use a trebuchet--but they never succeed. At this point, the deus ex machina the title refers to comes in, Locke has a vision of Boone standing on the hatch, covered in blood, repeating "Theresa falls down the stairs. Theresa falls down the stairs." In the vision, Locke is thrown back into his wheelchair and he sees a beachcraft crash on the island. It is one of the scariest LOST scenes of all time and I refuse to watch it with the lights out. This leads Locke to believe that the plane he saw was real and that the island was sending him a sign. So, in pure Locke fashion, he enlists Boone to help him find it. They do find it; but, when Boone is up in the plane using the radio, the plane falls from the canopy and Boone is severely injured. Later that night, Locke is seen banging on the hatch screaming the heavens about what he is supposed to do. It is at this time that an infamous moment in LOST happens, a light comes on inside the hatch and it shines right into Locke's face. Scary stuff. I'm sure everyone was talking about this for weeks after the episode aired.
Other than that, there are some really funny scene's between Jack and Sawyer about Sawyer's constant headaches and the fact that he needs glasses.
(About Sawyer's glasses)
Hurley: Dude, it looks like someone steamrolled Harry Potter.
Funniest. Line. Ever.