Plutarch was a Greek historian, biographer, essayist, and Middle Platonist known primarily for his Parallel Lives and Moralia . Thanks to his writings and lectures Plutarch became a celebrity in the Roman Empire. At his country estate, guests from all over the empire congregated for serious conversation, presided over by Plutarch in his marble chair. Many of these dialogues were recorded and published, and the 78 essays and other works which have survived are now known collectively as the Moralia . Plutarch’s best-known work is the Parallel Lives, a series of biographies of famous Greeks and Romans, arranged in pairs to illuminate their common moral virtues and vices. The surviving Lives contain 23 pairs, each with one Greek Life and one Roman Life, as well as four unpaired single Lives . Some of the Lives, such as those of Heracles, Philip II of Macedon and Scipio Africanus, no longer exist; many of the remaining Lives are truncated, contain obvious lacunae or have been tampered with by later writers. Extant Lives include those on Aristides, Pericles, Pompey, Julius Caesar, Cicero, Cato the Younger, Mark Antony, and Marcus Junius Brutus. Plutarch also wrote a series of biographies, including the biographies of Demetrius, Pyrrhus, Agis and Cleomenes, Aratus and Artaxerxes, Philopoemen, Camillus, Marcellus, Flamininus, Aemilius Paulus, Galba and Otho.