Love
Love is the overriding theme of the film, which is symbolized by the Heart of the Ocean diamond. The blossoming love affair between Jack and Rose is the central narrative of the film, one that leads them to make risky, fateful decisions in order to stay together. In the film, the upper classes are shown to be largely incapable of love: Ruth would prefer that her daughter enter into a loveless marriage with the steel magnate Cal Hockley so that they can preserve their riches. Rose's interactions with Jack, however, convince her that an authentic, passionate relationship is more valuable than any riches. Rose dropping the Heart of the Ocean diamond back into the sea at the end of the film, rather than turning it over to Brock, reflects the fact that love is a mysterious and powerful force beyond measure, something not reducible to material wealth.
Class
James Cameron once described the film as "Romeo and Juliet on the Titanic," but instead of staging a battle between Montagues and Capulets, Cameron dramatizes the hostility between the rich and the poor. Rose feels so suffocated by her the expectations of her wealthy family and friends that she nearly kills herself in the film's first act, and Cameron portrays the upper class to be overwhelmingly amoral. J. Bruce Ismay's arrogance dooms the ship, Cal Hockley's abusive behavior shocks Rose, and Rose's mother Ruth shamelessly uses her daughter as a pawn. Only Molly Brown, as an example of "new money," retains her moral center. The penniless artist Jack, on the other hand, values experiences over possessions, and encourages Rose to do the same. Cameron also shows how third-class passengers, caged below deck, perished at greater rates than first-class passengers, who bribed and cajoled their way onto lifeboats.
Time
Time is a key theme in Titanic, one that is conveyed primarily through the symbol of the clock. Cameron uses the ornate clock engraved in the first-class lobby of the ship as the meeting-place for Jack and Rose, which she dreams about at the end of the film. The clock represents the fact that Jack and Rose are able to experience a whirlwind romance together in a matter of days, but also that their time together is limited by the ship's tragic fate. As she is launching into her tale, elderly Rose says, "It's been 84 years...," symbolizing the chasm of time that now separates her current experience from her memories. Thomas Andrews is seen at the end of the film staring into a clock, contemplating the minutes he has left on earth before the ship sinks. Once the ship hits the iceberg, time becomes an urgent theme that determines how all of the characters act.
Power
Titanic is a ship, but it is also a powerful symbol, a gigantic object that embodies the fantasies that various male characters have about feeling powerful. Prideful characters like Cal Hockley and J. Bruce Ismay arrogantly project their own feelings onto the ship, regarding it as majestic and unsinkable. Cal even says, "God himself could not sink this ship!" Rose scolds Ismay for fixating so obsessively on the ship's sheer enormity. Jack entertains his own fantasies of power when he climbs the railing on the ship's bow and yells, "I'm the king of the world!" Captain Smith, the ship's leader, takes his power for granted to the extent that he misses critical warnings and speeds up to attract favorable press. The desperation of first-class passengers to retain their power, even under dire circumstances, is also on clear display. The sinking of the ship ultimately shatters all of these fantasies of power, showing man to be powerless in the face of tragic unpredictability.
Memory
Titanic is a film that unfolds largely through the memories of Rose Dawson Calvert. Cameron instills Rose's memories with the magnificent and opulent detail of a Hollywood production, suggesting that first-hand testimony will always be more powerful than any photographs or news items about the event. Rose's recollections, conveyed through voice-over narration over the course of the film, color the audience's perception of the events. After she tells her story, Rose says of Jack, "He exists now only in my memory...," given that he was not on the ship's manifest, and perished in the disaster. Rose ultimately dreams that she is back on the Titanic with Jack before passing away, reflecting the fact that she has finally reconciled her memories with her present.
Greed
Many of the film's characters are susceptible to avarice and greed. Rose's mother Ruth is so terrified of losing her possessions that she forces her daughter to enter into an unhappy marriage with an abusive man. Cal Hockley only knows how to express his affection for Rose by giving her exorbitant gifts like the Heart of the Ocean, and becomes furious when he realizes it is gone. When Jack goes to dinner in first class, Molly tells him dryly, "Remember, they love money, so pretend you own a goldmine, and you're in the club." The greediness of the White Star Line is portrayed by their refusal to load the ship with an adequate number of lifeboats, or when a crew member chastises Jack for uprooting a bench so that they can escape third class. The pervasive elevation of money over human life eventually disgusts Rose so severely that she abandons her mother, spits in Cal's face, and returns to Jack's side, even as the ship is sinking.
Loss
The story of the Titanic is, above all, a human tragedy that claimed over a thousand lives, an event made all the more tragic by how preventable it was at numerous points. Cameron makes liberal use of foreshadowing in order to heighten the emotional impact of the devastating casualties incurred by the event, such as when Rose notices the lack of lifeboats, or when Captain Smith's ignores iceberg warnings. No character emerges unscathed from the disaster. Even the survivors, Rose remembers, would spend their lives "waiting for an absolution that would never come." Characters like Captain Smith, Thomas Andrews, and William Murdoch are haunted in their final minutes by overwhelming guilt. Many passengers die trying to protect loved ones, and to remain calm in the face of certain death. The band playing on during the sinking symbolizes the struggle of the human spirit to remain joyful in times of dire loss.
