Historians will look back on our time and see that our civilization spends many millions of dollars educating people about the scourge of H.I.V. and AIDS, which has already taken 25 million lives and could infect 100 million people over the next eight years. But what they will find not so civilized is our failure to treat 95 percent of people with the disease. Given that medicine can turn AIDS from a death sentence into a chronic illness and reduce mother-to-child transmission, our withholding of treatment will appear to future historians as medieval, like bloodletting. Consider that there are close...