Her early essays, including "Notes on 'Camp,' " were collected in "Against Interpretation" (1966), her first major nonfiction book. She argued against critics who hunted for heady significance in a work of art at the expense of its sensual impact.
"In most modern instances," she wrote, "interpretation amounts to the philistine refusal to leave the work of art alone. Real art has the capacity to make us nervous. By reducing the work of art to its content and then interpreting that, one tames the work of art."
Susan Sontag characterized her motivations simply: to "know everything," starting with literature.
As a radical and incisive thinker, she protested and wrote against the Vietnam War, visiting Hanoi to understand the motivations of the Vietnamese resistance to the U.S. military.
She began examining the presentation of disease in popular culture after her diagnosis of cancer in her breast, lymphatic system and leg and was given a 20 percent chance of survival. She underwent a radical mastectomy and chemotherapy that cured her of the cancer.
In "Illness as Metaphor" and her book "AIDS and Its Metaphors" (1989), as well as countless interviewers, she condemned the idea of illness as a curse or plague, somehow a metaphor for social, cultural or moral decay. Illness is simply fact, she said.
Despite other health conditions, she remained productive, producing a best-selling novel, "The Volcano Lover" (1992), about Lord Nelson and his mistress, Lady Hamilton.
She spent much of her life in transit, living in Paris, Berlin and elsewhere while maintaining a home in what she considered the only livable spot in the United States -- New York. "And what I like about Manhattan is that it's full of foreigners," she said.
A restless voyager into the 1990s, she staged "Waiting for Godot" in Sarajevo. Even those who best understood her questioned her sanity to thrust herself into a war zone for the sake of art. "I didn't think I was invulnerable, because I had a couple of very close calls, and I don't think I'm a thrill-seeker," she said. "I just thought it's okay to take risks, and if ever I get to the point when I don't, then take me to the glue factory."