Book Review Justinian's Flea: Plague, Empire, and the Birth of Europe By William Rosen. 367 pp., illustrated. New York, Viking, 2007. $27.95. 978-0-670-03855-8 Plague and the End of Antiquity: The Pandemic of 541–750 Edited by Lester K. Little. 360 pp. New York, Cambridge University Press, 2007. $75. 978-0-521-84639-4