Samuel Johnson once called the medical profession "the greatest benefit to mankind." In the 20th century, the quality of that benefit has improved more and more rapidly than at any other comparable time in history. With all the capabilities of modern medicine's practitioners, however, we as a people are as worried about our health as ever. Roy Porter, a social historian of medicine the London's Wellcome Institute, has written an dauntingly thick history of how medical thinking and practice has risen to the challenges of disease through the centuries. But delve into its pages, and you'll find one marvelous bit of history after another. The obvious highlights are touched upon--Hippocrates introduces his oath, Pasteur homogenizes, Jonas Salk produces the polio vaccine, and so on--but there's also Dr. Francis Willis's curing of The Madness of King George, W.T.G. Morton's hucksterish use of ether in surgery, and research on digestion conducted using a man with a stomach fistula (if you don't know what that means, you may not want to know). Porter is straightforward about his deliberate focus on Western medical traditions, citing their predominant influence on global medicine, and he has produced a volume worthy of that tradition's legacy.