Executive producer J.J. Abrams may not have had much of an influence on “Lost” beyond its acclaimed “Pilot,” but bringing composer Michael Giacchino (most famous for his collaborations with Abrams and Pixar) into the fold was arguably his biggest contribution. Giacchino’s score is the most vital element in balancing the various tones of the show, managing to convey a sense of mystery and adventure, while also providing the show with its beating, overtly–sentimental heart. In the words of the show’s producers, “Instead of using music to enhance the scenes, Michael’s score gave life to the characters.”

In “Pilot,” Giacchino essentially hits all of the series’ tonal notes in four different tracks. Starting with “The Eyeland,” we get our first use of ambient, mysterious sounds as the series’ redemptive hero, Jack Shepherd, awakes in the middle of the jungle, sharing the viewer’s confusion and asking the series’ most prominent question, “Where the hell are we!?” Transitioning into “World’s Worst Beach Party,” Giacchino breaks out the driving percussion (played on actual plane fuselage) that would come to characterize so many of the show’s action scenes. Later in the episode, Giacchino’s “Hollywood and Vines” makes its triumphant debut. This iconic track perfectly underscores the characters’ many treks into the jungle, most prominently being used in nearly all of the season finales as the show’s main adventure theme. With “Credit Where Credit is Due” (the show’s main theme) the music completely slows down, becoming far more meditative as we see the characters begin to quietly reflect on the crash and all the destruction they’ve already gone through. “Lost” was always at its best in these dialogue–free moments, which truly allowed Giacchino to pull on the audience’s heartstrings. Whether it was a death or a reunion, a plane boarding or a plane landing, you could be sure that when the score took over, Giacchino would deliver on the montage.

Of the show’s many character motifs, no one was better served by the score than the enigmatic survivalist John Locke. “Locke’d out Again,” his main character theme, was introduced in his sensational first centric–episode “Walkabout.” The track bridges the past and present in one of the series’ greatest moments, revealing that Locke was previously paralyzed and that the Island restored his ability to walk. The score soars over this incredible moment, but the track will later be used to devastating effect, as the various tragedies that ultimately resulted in Locke’s paralysis are slowly unveiled throughout following episodes.

When I think back on the polarizing finale, all I can think of is the summation of Giacchino’s score building to its emotional climax as all of my favorite characters got to “move on” into the great unknown. The last track of the show, “Moving On” demonstrates his ability to draw on his signature motifs and combine them to great effect. Using a combination of “Life and Death” and “There’s No Place Like Home,” perhaps the two most emotionally resonant tracks he ever wrote, Giacchino managed to turn a glorified wrap–up party into a bitter sweet send–off for the characters who made the show one of television’s best, regardless of any unresolved mysteries and infuriating ambiguity.

“Lost” is a show about dealing with tragedy and grief, and “Life and Death” accompanies several of the series’ most poignant scenes, notably several main characters’ heartbreaking sendoffs. Coupled with the “Home” theme, which underscored several of the later seasons’ most sentimental moments, Giacchino is able to close out the show while recalling some of its finest hours. “Life and Death’s” first appearance on the show plays as Jack tells the survivors that “if they can’t live together, then they’re going to die alone.” In the end, we see Jack flash between his death on the Island and his reunion with his fellow survivors in the afterlife and the message is clear; because these people finally learned how to live together and found the home they needed, they were able to let go of life and move on with the people they truly cared about. Is it tacky? Sure, but the cast and crew always managed to sell it, with Giacchino as the show’s real MVP.