Healing vs. Denial
One of the more complex themes in The English Patient involves the extraordinary emotional baggage that the main characters bring to the start of the novel. When each character arrives at the Italian villa, it seems they are physically and/or emotionally wounded: Hana lost her father in an accident, Caravaggio lost his thumbs at the hands of the German army, Kip lost his mother and his surrogate father, and the English patient lost both the love of his life and his own body. Each character is given the chance to remember his or her story or speak it aloud, and it is the process of shedding light on the dark corners of their respective souls that seems to bring healing to each one of them. However, denial is a constantly threatening force: Hana refuses to admit the villa is unsafe, Kip has yet to come to terms with his race, and the English patient cannot even acknowledge his own name, because of its entanglement with a separate, politicized identity. The question of how much each character heals and how much each character denies is central to the novel.
Passion vs. Frigidity
In this novel, the union and disunion of characters is often based in their ability to communicate, and their inherent tendencies towards passion or frigidity. Almasy is exceedingly rational and cerebral, and seems completely immune to matters of the heart. Instead, he is concerned with knowledge, with learning in the textbook sense. In Katharine, however, he encounters the opposite - a true firebrand who lives moment to moment wrapped in the flames of passion. Indeed, the two learn from each other: Almasy learns to love, and Katharine begins to become more curious. Their differences, however, are what ultimately undo them: Katharine cannot stand Almasy's coldness, his ability to so clinically separate himself from her in public. The irony, of course, is that it is the passion - the raging furious passion - of her husband Geoffrey that ultimately leads to her death, long after the affair with Almasy has ended. As he recounts the story, Almasy is surprised at how all-consuming passion can be - he can no longer remember all the details of his own politicized role in the world, because all he cares to remember is Katharine and the way she changed him. Hana and Kip struggle with similar issues, in that both have built strong defenses against getting to know people, perhaps because of the deaths of their respective parents. Hana reconnects with life by the end, but we're not quite sure whether Kip does - we know only that he escapes and begins anew.
Drive towards Life vs. Drive towards Death
One of the subtler aspects of The English Patient is revealed in the progression of character arcs - in the ability of our protagonists to either reconnect to life and find reasons to live or to embrace death. The English patient, for instance, hangs on to life at the outset, the glimmers of his romance with Katharine so deep in his memory, so fresh on his lips - but by the end of the novel, after recounting the story, he seems ready to die. Indeed, when Kip confronts him with a gun, he asks Kip to shoot him. Hana, meanwhile, begins the novel moving firmly towards death - she is obsessed with it, even, to the point of wanting to stay in the unsafe villa simply to be with her patient. But as she begins to see what waits for her once she gives up her guilt and leaves him, Hana begins to drift back into the world. The patient, after all, is a substitute for her father - a man who died after being burned. Hana cannot forgive herself for having been so far away when her father died, and thus clings to the patient who represents him. As she learns to forgive herself, she loses her attachment to death and renews her engagement in life.
The Desert
The desert is an inextricable aspect of Ondaatje's novel in that it provides so many dualities for imagery, theme, metaphor - the heat of the day, the cold of the night; the seeming serenity and then the suddenness of storms; the quiet pierced by the racket of war. Remembering his experiences in the desert, it seems like Almasy cannot bring up his memories chronologically. Instead, the desert seems to refract memory. And everywhere is the image of fire - the Bedouin boy dancing in the moonlight, the plane falling out of the sky, the man on fire before he becomes the English patient. It seems almost tamable, but his experiences there suggest the reverse: the volatile desert, able to consume and ravage at will, is always in control.
Loneliness vs. Connection
All of the characters come to the villa without attachment. Hana has nothing in the world but her patient, Kip soon loses his sapper partner, Caravaggio is on the run, Almasy has lost his love. It is crucial, then, to notice how alone these characters are - how they could die in the villa without anyone noticing. Upon reaching the villa, they seem happy in their isolation, but soon enough they begin to connect and to see the threads that they have in common. By the end, even Hana has stopped using the library as a refuge, and instead uses it as a place to playfully prank Caravaggio and Kip.
Surrogate Parents
The characters in The English Patient cling to surrogate parents in order to relive and heal from their childhood traumas. Hana lost her father in a terrible accident in which he was burned to death. She was across the world from him and has never forgiven herself for being so far away, and so she chains herself to the similarly burned English patient to make sure that he is given the chance to end his life in peace. The English patient is clearly a substitute for her father, and the desert a symbol for the physical and emotional vastness between Hana and her dead parent. Kip, meanwhile, has lost his mother, and we see that in Hana's arms, he finds the comfort of a surrogate mother. There is love and lust at first with Hana, but soon it becomes clear that all he needs is the embrace of a woman who he can project as his mother. And just as Almasy made love to Katharine's dead body, now he has Hana revering his dying body, allowing him to die having achieved peace.
Debt
Our protagonists repeatedly seem concerned with what they "owe" others. After Hana stays to help Kip demine the bomb, Kip is resentful that Hana might now expect something from him - that he owes her for her remaining with him under such dangerous circumstances. On the other hand, Hana feels as if she owes everything to the English patient, and cannot survive elsewhere because she is in debt to him. Kip meanwhile believes Almasy owes him a debt for all the lives that were ruined by Indian subservience to the British. Indeed, Kip believes that Almasy, as a representative of the West, owes him something considerable, and nearly takes his life over it.