“The dancing sickness took place during the latter part of the fifteenth century. Bubonic plague--the black death--decimated Europe near the end of the fourteenth. Whooping cough near the end of the seventeenth, and the first known outbreaks of influenza near the end of the nineteenth. We've become so used to the idea of the flu--it seems almost like the common cold to us, doesn't it?--that no one but the historians seem to know that a hundred years ago it didn't exist.”