An anthropologist's erudite report on how our ideas about the body (and society) are undergoing a dramatic shift. Martin (Anthropology/Johns Hopkins; The Woman in the Body, 1987) and her research assistants conducted over 200 interviews with people in diverse Baltimore neighborhoods to learn how ordinary people understand the immune system and how their understandings have shaped their thinking about health, illness, and fitness. By also working in an immunology research lab, as a volunteer buddy to HIV-positive individuals, and as an AIDS activist, she was able to study the attitudes of people with impaired immune systems and of scientists researching immunology. Through analysis of the popular culture of the 1940s and 1950s, she shows how the body was once thought of as a fortress with its defenses primarily at its surface. The emerging view, she finds, sees the body as defended internally by a complex immune system able to respond swiftly to changes. This adaptability, or flexibility, is seen as a highly desirable attribute not only for the immune system but for individuals and organizations, and those lacking it are perceived as being less fit for survival -- biologically or economically. Martin comments on the dangers of such a view and speaks for the contrary values of stability and security. Portions of her material have been previously published in professional journals and presented in university seminars and lectures. Here she is attempting to write for the general reader, lacing the text with cartoons, drawings, and magazine ads and quoting liberally from interviews. Nevertheless, newcomers to the theory of complex systems, or chaos theory, will find this a challenge. A provocative study, albeit one that occasionally reads like a PhD thesis, of how scientific ideas operate in the real world.