Disease is an abnormal phenomenon that occurs in the human body, often accompanied by varying degrees of deviation from the body’s regular state. However, as a phenomenon that has always coexisted with human society, disease has often been endowed with human-centered descriptions and meanings due to its historical and social nature. In Illness as Metaphor, American writer Susan Sontag traces and compares the differing social evaluations of tuberculosis, cancer, and AIDS. She reveals the underlying mechanisms through which physical illness becomes imbued with moral significance and calls for a return to the literal understanding of disease—treating both illness and patients as they are, not as symbols.

I. What Is a Metaphor?

Before discussing disease-related metaphors, it is necessary to clarify the concept of “metaphor.” Although Sontag does not define the term or explain its specific usage in her book, considering her stature as a prominent literary theorist and critic, we must not overlook metaphor as a rhetorical and literary device. Understanding metaphor helps us comprehend how symbolic meanings are assigned to diseases and why such human-constructed associations carry immense influence and real-world power.

The Greek root of “metaphor” is metapherein, meaning “to transfer” or “carry over.” Aristotle, in Poetics, wrote: “A metaphor consists in giving the thing a name that belongs to something else: the transference being either from genus to species, species to genus, species to species, or by analogy.” Since the 20th century, especially with the cognitive turn in linguistics, metaphor has come to be understood not merely as a decorative device, but as a core element of how language and meaning interact. For instance, when we refer to the support of a table as a “leg,” we reveal how our perception of a table’s structure relates cognitively to our understanding of a human body.

American cognitive linguist George Lakoff went further, arguing that “metaphor is thought itself.” The relationship between elements in a metaphor is not necessarily grounded in natural similarity; rather, it is often a cultural or cognitive construction. For example, calling someone a tiger could signify strength or cruelty, but the tiger itself is not inherently tied to either trait—similarity is projected and constructed by the speaker. Moreover, the very thought processes we use to determine similarity are shaped by language itself. Humans rely on metaphor from the very beginning to navigate the world: we understand the unfamiliar by comparing and relating it to what we already know.

Metaphors are typically rooted in three sources: emotional needs, rhetorical strategy, and cognitive necessity. Emotionally, comparisons with familiar things help express feelings more vividly—for example, saying someone is “as fierce as a tiger” rather than simply “fierce.” Rhetorically, metaphors create aesthetic pleasure by departing from conventional expressions. Cognitively, metaphors help us understand the unfamiliar through the familiar. In practice, these three sources often intertwine. Once established, metaphors produce social effects. Widely accepted metaphors lose their rhetorical novelty and become perceived as natural linguistic or conceptual forms. Words like “intersection,” “mountaintop,” or “isosceles triangle” are rarely recognized as metaphors today, yet they reflect metaphorical thinking. Thus, metaphors exert undeniable social influence.

II. Tuberculosis and Cancer

Tuberculosis and cancer were once diseases that medical science could not conquer. Tuberculosis had clear, visible symptoms: alternating pallor and redness, emotional highs and lows, persistent coughing, weight loss, and fever. It was believed to heighten emotions, appetite, and sexual desire. Since the disease was untreatable in the 19th century and invariably fatal, it created the impression of life burning out swiftly—what Sontag described as “accelerating and illuminating life, making it transcendent.” The patient’s gradual emaciation and constant coughing contributed to a sympathetic and tragic image. In literary depictions, tuberculosis came to be seen as a noble, romantic illness. Frailty and thinness were aestheticized as signs of gentleness and delicacy. The disease was even seen as the mark of a sensitive, artistic temperament. However, by the 1920s, medical breakthroughs made tuberculosis curable, and its myth dissolved.

In contrast, cancer can develop in virtually any organ. It often shows no obvious symptoms in the early or even middle stages, and is typically diagnosed only in late, incurable phases. Cancer depletes the patient’s vitality, suppresses sexual desire, and steadily consumes the body in an irreversible decline. If it affects sensitive areas—like the cervix, testicles, breasts, or colon—it becomes even more taboo. Cancer patients are seen as repressed, depressed, and lacking in willpower. Unlike tuberculosis, cancer does not suggest a melancholic, creative temperament; instead, it reflects physical weakness and emotional fragility. Even today, despite advances in treatment, cancer remains closely associated with death. Families, out of sympathy or shame, often hide the truth from patients.

III. Schizophrenia and AIDS

After tuberculosis and cancer became manageable, schizophrenia and AIDS inherited their metaphorical burdens. Schizophrenia replaced tuberculosis as the new “artist’s illness,” while AIDS took over cancer’s role as a source of moral condemnation and psychological stigma. If schizophrenia is considered a disease, it belongs to the realm of the psychological. We will examine the body–mind dualism later, but psychological illnesses are often seen as linked to intellectual or philosophical traits. For instance, Nietzsche and Hölderlin’s schizophrenia has often been romanticized as a radical rejection of an unsatisfactory world.

In contrast, AIDS is indisputably a physical disease. Like cancer, AIDS became associated with moral judgment. While schizophrenia, with its chaos of thoughts, can still be perceived as a marker of genius, AIDS was quickly framed as the result of moral degradation. AIDS is not a single disease but a term for a clinical condition—Acquired Immune Deficiency Syndrome—characterized by the collapse of the immune system and increased susceptibility to infections like syphilis, cancer, or tuberculosis. It is a chronic illness with an incubation period ranging from several years to decades, marked by fatigue, fever, weakness, and appetite loss. Socially, AIDS has been wrongly reduced to a single cause: rampant and especially homosexual sex. Patients are morally condemned, and both they and their families face shame and social exclusion.

IV. Metaphor and Myth

1. The Formation of Metaphor

Two basic conditions are necessary for metaphors to take shape. First, the object being perceived must leave room for interpretation. For instance, a wine glass, once fully understood in terms of its structure and function, may no longer inspire metaphorical associations. Second, the two entities being linked must share some degree of similarity. The deep-rooted metaphors associated with tuberculosis, cancer, schizophrenia, and AIDS developed precisely because they satisfied these two conditions.

Each of these diseases has historically posed challenges to medicine. In the absence of scientific understanding—regarding origin, development, or treatment—they inspired questions and fear, which in turn fueled imagination. Their potential to threaten life imposed an additional explanatory burden. In this context, metaphor emerged as a tool to comprehend the unknown.

However, different diseases followed different metaphorical trajectories. Tuberculosis was considered a “literati disease” largely because of the visual contrast it presented: coughing, frailty, and emaciation suggested low physical energy, while intense emotions and desires indicated heightened spiritual energy. This contradiction created a kind of existential tension that allowed for idealization. In contrast, cancer—characterized by declining appetite, organ deterioration, reduced sexual desire, and physical atrophy, often in private or shame-associated areas like the breasts or genitals—evoked disgust or fear, making it prone to vilification. Cancer gradually came to represent an “internal barbarism.”

While it is understandable that different symptoms generate different metaphors, one must ask: why does coughing and heightened desire signify the fragile genius, while atrophy and hardening of organs suggest moral weakness? This may be explained by complex layers of social psychology, which Sontag does not fully explore. However, the contrast between schizophrenia and AIDS highlights an essential point: differing views of the body and the soul.

In pre-Nietzschean Western thought—from Plato to Descartes—the body was positioned as the lower half of a dualism, a repressive and limiting force subordinate to the soul. Tuberculosis, affecting the upper body—especially the chest and lungs, where the heart and breath are located—was thus associated with spirit and emotion, viewed as a “disease of the soul.” Such a disease could not be imagined to affect shame-inducing body parts like breasts or genitals. Diseases in those regions evoke shame and disgust and lead to negative social judgments.

Schizophrenia represents the extreme form of the “disease of the soul.” It stems from the disintegration of consciousness—but consciousness is socially constructed. Thus, a schizophrenic’s confusion reflects not just internal chaos...