LONGI'NUS, DioNvsrus CAssius, a Platonic philosopher and famous rhetorician, VMS b., according to some, at Emesa, in Syria, and according. to others, at Athens, about 213 A.D. In his earlier years, lie traveled a great deal in the company of his parents, aud made the acquaintance of many celebrated scholars and philosophers. He studied Greek literature at Alexandria, where he was for a considerable time the pupil of Ammonius and Orimen, and subsequently settled as a teacher of rhetoric in Athens, where he soon acquired' a grcat reputation. His knowledge was immense: he was called a " living library " and a " walking museum," but his taste and critical acuteness were no less wonderful. He was probably the best critic of all antiquity. In an age when Platonism was giving place to the semi-oriental mysticism and dreams of Neoplatonism, Longinus stands out conspicuous as a genuine disciple of the great master. Clear, calm, rational, yet lofty, he despised the fantastic speculations of Plotinus, who consequently mould not admit that Longinus was a philosopher, but—since he stooped to criticise the diction and sty-le of Plato—pronounced him a mere philologist. In the latter years of his life,
he accepted the invitation of Zenobia to undertake the education of her children at Pal myra; but becoming also her prime political advisor, lie was beheaded as a traitor, by command of the emperor Aurelian, 273 a.-D. Longinus was a heathen, but a generous and tolerant heathen. Of his works, the only one extant (and even that one only in pint) is a treatise, Pori HI/poems (On the Sublime). There are many editions of Longi nua's treatise, of which those by Morns (Leip. 1769), Toupius (Oxf. 1778, 2d ed. 1782, 3d ed. 1806), Weiske (Leip. 1809), and Egger (Paris, 1837), are among the best. See also Ruhnken's Dissertatio de Vita et Seriptis Longini.