The answer is Polybius. He was a Greek historian from the Hellenistic period, known for writing The Histories and being a fervent admirer of the Romans although they repeatedly invaded his homeland (Megalopolis, Arcadia) and beat its armies. Two of the main factors behind his atypical fondness were his understanding of Greece's political problems that made appreciate Roma's ways and his friendship with Romans aristocrats, a link that resulted in him getting preferential treatment when he was taken as hostage.
