Most moderate-sized American cities are dominated by two structures: bank buildings and hospitals. The former are often large and new because it’s where we like to put our money. The latter are large because we’re afraid to die and don’t want to be sick. Both are particularly modern structures. You could travel to ancient Pompei, were it to be completely reconstructed. You would find neither bank nor hospital. Of the two, hospitals came first. Ancient Greece and Rome had doctors. They worked with herbs, and even performed fairly simple surgeries. The “Hippocratic Oath,” sworn by modern doctors as part of...