3. An Argive, the son of Mnasiades, descended from an illustrious family at Argos, came over to the court of the Egyptian monarch Ptolemy Philopator, just before his campaign against Antiochus III., in B. C. 217. Polycrates was of great service in drilling and encouraging the Egyptian troops, and he commanded the cavalry on the left wing at the battle of Raphia, in B. C. 217, in which Antiochus was defeated, and which secured to Ptolemy the provinces of Coele-Syria, Phoenicia, and Palestine. Although Polycrates was still young he was second to no one, says Polybius, in the king's court, and was accordingly appointed by Ptolemy governor of Cyprus.
The duties of this office he discharged with the utmost fidelity and integrity ; he secured the island for Ptolemy Epiphanes, the infant son and successor of Philopator, and on his return to Alexandria about B. C. 196, he brought with him a considerable sum of money for the use of the monarch.
He was received at Alexandria with great applause, and forthwith obtained great power in the kingdom; but as he advanced in years, his character changed for the worse, and he indulged in every kind of vice and wickedness. We are ignorant of his subsequent career, in consequence of the loss of the later books of Polybius ; but we learn from a fragment of the historian that it was through his evil advice that Ptolemy took no part in military affairs, although he had reached the age of twenty-five. (Plb. 5.64