Aristobūlus in Harpers Dictionary of Classical Antiquities

（Ἀριστόβουλος). A Greek historian, who in his youth accompanied Alexander the Great on his campaigns. In his eighty-fifth year, when living at Cassandrea in Thrace, he wrote a work upon Alexander, in which he recorded his careful observations on geography, ethnography, and natural science. The book is highly praised for its trustworthiness, but only fragments of it have reached us. He and Ptolemy were the chief authorities for Arrian's Anabasis.

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