I noticed that someone posted before asking what started all the events of Lost. I think the show begins and ends with the Swan station, and along those lines, Desmond. During the events of "Live Together, Die Alone" Desmond and Locke failed to push the button, resulting in a system failure. Desmond went down under the Swan to turn the failsafe key, negating the electromagnetic energy within. The discharge gave Desmond the power to the see flashes of the future, and made the Island more visible. Desmond's flashes of the future allowed him to tell Charlie that he had to go down to the Looking Glass, turn off the jamming equipment, and die. He was able to contact Penny, then died. When the failsafe key was turned, Penny's people were able to detect the electromagnetic anomaly, and this same electromagnetic was probably the way that Widmore found the Island. Widmore sent a freighter to the Island to capture Benjamin Linus, and a result of this Ben turned the frozen donkey wheel to move the Island. The helicopter from the freighter and Frank Lapidus aided the Oceanic Six and Desmond to leave the Island. As a side effect of moving the Island, the island began to skip through time. Locke turned the wheel the rest of the way, and was transported off the Island to try and bring back the Oceanic Six to "save" the Island. Locke's comment to Jack about talking to his father, Christian Shephard, was the impetus for Jack to want to get back to the Island, and in a domino effect, the rest of the Oceanic Six, with the help of Ben, made it back to the Island, with some of them ending up in 1977. Now here is where I get into speculation. We know that sometime before in around 6 hours (in 1977) according to Faraday there is "an incident" at the Swan. Jack could try to carry on Faraday's plan to change the future and prevent the Incident from happening by detonating Jughead. We have seen so far that so far the Losties' actions to alter the future (Sayid shooting Ben, Faraday going to see Ellie in 1977) have only been met with failure, so I think it is safe to assume that if Jack tries to prevent the Incident from happening, he will fail, and possibly even cause the Incident to occur. As a result of the Incident happening, DHARMA cements over the Incident Room and installs the computer, requiring a button to be pushed every 108 minutes to save the world. Years later, Desmond arrives on the Island, is intercepted by Kelvin, and is put to work in the Swan pushing the button. On September 22nd, 2004, Desmond leaves the Swan to follow Kelvin, and accidentally kills him. The Swan has a mini system failure that causes Flight 815 to break into 3 pieces in mid-air and crash onto the Island with 48 survivors, including John Locke. Locke will eventually convince Desmond to not push the button, and we are back to where we started. The Swan is undoubtedly the most important DHARMA station in Lost, as if my theory about the Incident is true, is the cause of everything that has happened on the show.