"The advancing edge of health care" or "pseudo science"? Alternative medicine can be either, depending on the therapy and who's talking about it, and both sides make compelling cases in this overview of the subject. But no one disagrees with former New England Journal of Medicine editor Marcia Angell when she calls it "big business." And this report doesn't pretend to be the final word. "We don't know everything about illness and health," Harvard medical historian Ted Kaptchuk says simply.