"Any important disease whose causality is murky, and for which treatment is ineffectual, tends to be awash in significance"

Susan Sontag, in her examination of illness and its metaphors, articulates how diseases that elude clear scientific understanding become heavily loaded with symbolic meaning. When causality is "murky", that is, when science and medicine cannot decisively explain the origins or mechanisms of a disease, uncertainty prevails. With that uncertainty comes a vacuum, and into this vacuum pour theories, speculations, and cultural anxieties. The lack of effective treatments compounds the issue. When medicine cannot offer a cure or even meaningful alleviation, patients, clinicians, and societies search for alternative explanations and remedies, often outside the bounds of empirical science.

The implication is that diseases are not simply biological entities; they become cultural artifacts, repositories for fears, prejudices, and projections. In the past, diseases like tuberculosis, syphilis, and later, cancer and AIDS fit this description. Their mysterious origins, unpredictable courses, and frequent lethality led people to convey broad moral, philosophical, or even mystical significance onto them. Illness becomes a metaphor, a stand-in for deeper societal anxieties and desires. For example, cancer has been linked with repression and decay in the popular imagination, AIDS with moral panic and social stigma, and mental illnesses with various cultural anxieties.

The "wash" of significance Sontag describes refers to the overlay of meaning added onto the literal fact of disease, meanings often based on myth, superstition, or social prejudice rather than scientific understanding. People search for patterns, root causes, or blame. Patients may internalize shame or guilt, and entire populations may direct fear or resentments toward stigmatized groups. These metaphorical associations, Sontag argues, are not just descriptive, they have real-world consequences, shaping medical practice, public policy, and social relations. Where knowledge and cures are lacking, significance rushes in, and with it, complexity, confusion, and often harm. The persistent presence of metaphor reminds us both of medicine’s limits and of our enduring need to make sense of suffering.