Library shelves groan under an insupportable mass of volumes about the dreadful flea-borne pestilence that spread across Europe in the middle of the 14th century -- the number of books being equaled only by the scores that deal with the very similar plague that killed thousands in London three centuries later. The Black Death, the Awful Malady, the Vast Pestilence, the Great Mortality, the plague has been called by many names, and is in many senses a perfect topic for the lazy historian -- the subject matter is adequately horrifying, the known descriptions are vividly readable, the social implications are sufficiently varied to allow for the kind of wild speculations that make for a book publicist's dream.