The genre of biography was invented by the ancient Greeks in the early 4th century BC. It evolved from the tradition of delivering prose orations at the funerals of distinguished men. Our earliest examples are by Athenians honouring leading Greek statesmen: for example, Xenophon’s Agesilaus, which praises the deceased king of Sparta by presenting a chronological account of his achievements. The genre evolved rapidly. Once the era of fabulous libraries had been initiated by the Ptolemies with the Musaeum at Alexandria in the early 3rd century BC, the research resources available to ancient biographers multiplied. They had access not only to flattering obituaries but also to any works the individual had himself authored, to the critical accounts written by his enemies and to satirical attacks made on him on the comic stage. By the time of Plutarch of Chaeronea (c46–120 AD), the most gifted and influential ancient life-writer, there were usually several earlier biographies of any historical figure available, each one synthesising diverse sources.