Illness as Metaphor is a 1978 medicinal critical essay written by Susan Sontag. In the essay, she criticizes the language used to describe the deadliest diseases of the twentieth century and the people who unfortunately suffer from them.

My point is that illness is not a metaphor, and that the most truthful way of regarding illness—and the healthiest way of being ill—is one most purified of, most resistant to, metaphoric thinking . . . It is toward an elucidation of those metaphors, and a liberation from them, that I dedicate this inquiry.

She makes comparisons between cancer and tuberculosis, saying that they are affiliated with similar psychological characteristics in the patients. Furthermore, she explains how the language used to describe these diseases is very disrespectful and discouraging to the patients, and those who use it, essentially, blame the patients for their tragic fates.

With the modern diseases (once TB, now cancer), the romantic idea that the disease expresses the character is invariably extended to assert that the character causes the disease—because it has not expressed itself. Passion moves inward, striking and blighting the deepest cellular recesses.

Depression is melancholy minus its charms.

Sontag explains how medical personnel should avoid using metaphors when referring to these diseases, as it makes the patients feel weak and responsible for what is happening to them. Many people believed that tuberculosis was God’s punishment to those who sinned and cancer was a disease that affected only those who lacked passion, fiery will, and feelings of love and lust.

Illness is the night side of life, a more onerous citizenship. Everyone who is born holds dual citizenship, in the kingdom of the well and in the kingdom of the sick. Although we all prefer to use the good passport, sooner or later each of us is obliged, at least for a spell, to identify ourselves as citizens of that other place.

Sontag argues that both the doctors and the patients should focus on the treatment and promote a healthy diet and lifestyle instead of ‘romanticizing’ the diseases, as the patients might feel depressed and guilty, and think that the fate they’re experiencing is happening because of their own emotions.

Theories that diseases are caused by mental states and can be cured by will power are always an index of how much is not understood about a disease.

These are contrasts drawn from the popular mythology of both diseases. Of course, many tuberculars died in terrible pain, and some people die of cancer feeling little or no pain to the end; the poor and the rich both get TB and cancer; and not everyone who has TB coughs. But the mythology persists.

Contrary to her essay, other authors and writers argued that the metaphors have in fact helped many patients cope and overcome their mental or physical sufferings.

Any important disease whose causality is murky, and for which treatment is ineffectual, tends to be awash in significance. First, the subjects of deepest dread (corruption, decay, pollution, anomie, weakness) are identified with the disease. The disease itself becomes a metaphor. Then, in the name of the disease (that is, using it as a metaphor), that horror is imposed on other things. The disease becomes adjectival. Something is said to be disease-like, meaning that it is disgusting or ugly.