Cassius Longinus was a rhetorician and philosophical critic. He was perhaps a native of Emesa in Syria. He studied at Alexandria under Ammonius Saccas and Origen the Pagan, and taught for thirty years in Athens, one of his pupils being Porphyry. Longinus did not embrace the Neoplatonism then being developed by Plotinus, but continued as a Platonist of the old type and his reputation as a literary critic was immense. During a visit to the east, he became a teacher, and subsequently chief counsellor to Zenobia, queen of Palmyra. It was by his advice that she endeavoured to regain her independence from Rome. Emperor Aurelian, however, crushed the revolt, and Longinus was executed.