You shouldn't drink."

As others have noted, alienation is a theme of modernism, especially after World War I left a younger generation wondering what all the loss of life of an extremely bloody and seemingly futile world war could possibly mean. How could supposedly civilized nations engage in such barbarity? The alienation that people felt in a world that seemed to have come unmoored, in which all the old values seemed to have lost their meaning, is also revealed through the stark dialogue. The husband and wife often talk past each other rather than to each other, and in this passage, the husband is hostile to the wife, saying "You give a damn about so many things I don't." Finally, the hopelessness of the husband's physical situation, dying of gangrene, mirrors the hopelessness inside the alienated modern person's soul. 

The story is very reflective of Modernism, as are many of Hemingway's other works, such as his first two novels, The Sun Also Rises and A Farewell to Arms.

The structure of the narrative is Modernistic as Hemingway shifts back and forth from the traditional narrative form to the italicized passages that reveal the protagonist's private thoughts and memories. Although the italicized passages are not written in first person or stream of consciousness, they are innovative and effective in exploring the psychology of Harry's inner life, his feelings and memories. Another unusual technique of structure is employed in the story's conclusion as Hemingway moves back and forth between events happening in reality and events happening only in Harry's mind as he approaches death--without distinguishing reality from hallucination.

Two themes common in Modernism are found in the story: alienation and Nihilism. Harry has lived a life of alienation, emotionally distant from his several wives and never identifying with or belonging to the wealthy society in which he has lived, courtesy of his most recent wife's money. As he dies, no spiritual faith sustains him. He has no thoughts of a Supreme Being or an afterlife. He thinks only of all he intended to write but did not write. He worships only the gift he squandered.

Finally, an especially interesting element of Modernism in the story is Hemingway's employment of allusion. Harry's tough and unsympathetic observations about his former friend Julian's destruction is an easily identified reference to F. Scott Fitzgerald, Hemingway's former friend who had suffered a severe emotional breakdown.

As others have noted, the stream-of-consciousness style Hemingway uses in "The Snows of Kilimanjaro" is associated with modernism. It's important to note, however, that stream-of-consciousness is not used by modernist writers simply as window dressing but comes from a deep desire to express their belief that knowledge is subjective, not objective. These writers, as Hemingway does, almost entirely dispense with the omniscient, all-knowing narrator because they didn't want to inject false certainty into their narratives. Instead, we see the action in the story in subjective terms as it is experienced by a dying man.

Hemingway also uses the spare, unembellished prose typical of the modernists, who wanted to get away from Victorian ornamentation.

In his treatment of a story about dying, Hemingway is strikingly modernist. Victorians loved sentimental and religious deathbed scenes, something modernists turned away from. Like a good modernist, Hemingway strips Harry's death of any false sentiment or religion. Religion is utterly missing from this story: after the shock of World War I's carnage, nobody is a believer. There is no praying, no invoking of angels, God, Jesus, or heaven. Harry's relationship with his wife is laced with fracture and bitterness, too, not sentimental deathbed reconciliation. He can be acidic as he speaks to her. They, for example, have the following dialogue:

“You bitch,” he said. “You rich bitch. That’s poetry. I’m full of poetry now. Rot and poetry. Rotten poetry.”
“Stop it. Harry, why do you have to turn into a devil now?”
“I don’t like to leave anything,” the man said. “I don’t like to leave things behind.”

In both style and content, Hemingway is doing something new, something that would have shocked earlier generations in its brutal honesty.

The stream-of-consciousness narrative technique is much in evidence in Hemingway's “The Snows of Kilimanjaro.” This technique was widely used by modernist writers as a way of giving the reader an insight into the subjective mental states of the characters depicted in their poems, novels, and short stories.

As is often the case in modernist works, the use of stream-of-consciousness in “The Snows of Kilimanjaro” highlights the sense of alienation from the world of a particular character. In this case, Harry is completely disillusioned with the world. He realizes that his life has been nothing but a sham, and resents the fact that his talent for writing has deserted him. Unable to spend his last remaining hours in the objective world, he retreats to the subjective realm, a world of fleeting thoughts and feelings captured by the stream-of-consciousness technique.

As he lies dying, Harry slips in and out of consciousness. But given his alienation from the world around him, a characteristic theme in modernist writing, the distinction between consciousness and unconsciousness becomes blurred to the extent that Harry loses his grip on reality. But then—in true modernist fashion—reality, as it existed in Harry's life, wasn't all that real to begin with.

Ernest Hemingway became famous in part for his introduction of a clean, terse writing style, approximate to a journalist's approach of letting the "facts speak for themselves," and "The Snows of Kilimanjaro" is a case in point. The story is modernist in terms of both form and content. The narrative employs innovative techniques that draw in the reader, making him or her work to realize the meaning of the piece, even as the protagonist is pondering the meaning of his (waning) life. Further, "Kilimanjaro" depicts themes - sex, class hostility, alcoholism, graphic recounts of war - that at this point in literary history (1936) were rarely dealt with as directly. And he does so in economical yet devastating prose.

Modernist technique opens the story; it begins abruptly with dialogue rather than any attempt at a descriptive introduction or presentation of the plot. We can't tell who is speaking, to whom or what the issues are. We get a sense there are vultures hovering, but they are not indicated by name, and we don't know what their prey is. The introductory quote about the mountain's history and the mysterious dead leopard is tantalizing, but unexplained: what was the leopard doing at that height? What does it have to do with the story? The effect is to make the reader a bit of a sleuth; s/he has to read closely to ferret out the details of the story, to learn that the buzzards loom about Harry as he is dying from gangrene to the leg, attended by his rich, privileged wife and the African natives that accompany them on safari. We are confused about what will happen to Harry, even as he is himself facing the unknown; we take in the enormity of his situation as he begins to realize it himself.

This formal technique and innovative presentation of point of view are elements of Modernism.

In addition, the subject matter of the narrative is modern: it is graphic; sexually explicit; psychologically penetrating; and includes social and class critique contemporary for its time. The story acts as a retrospective of Harry's life as it begins to dawn on him that he is dying. Harry recounts in explicit detail his experiences of war and of love. He tells of "urine-soaked roads" and the soldiers he skied with in Austria that he would eventually kill. We do not get the sense he is an unquestioning proponent of the war.

Harry is angry about a lot of the history of his life, and much of his anger seems to center, in psychological terms, on his wife. She is a "rich bitch." Because of her, he will never realize his potential or cover the subjects he intended to as a writer. She has "broken his balls," so to speak, sexually and as a man -- because she has the money in the family, she takes power from him. Increasingly easy on the cushion of privilege and wealth she provides, he gets nothing done, fritters away the time on frivolous ventures like the current safari and now has encountered an accident that will end his life. Like the gangrene in his leg, he is rotting away, and as much as he blames himself, he also directly blames his wife. Through Harry's perspective, Hemingway presents the classic Freudian trope of the castrating female.

Thus in the employment of formal technique, subject matter and social commentary, "The Snows of Kilimanjaro" is an excellent example of Modernism.