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.
In the preface to his work On Ends, which is preserved in Porphyry's Life of Plotinus, Longinus himself relates that from his early age he made many journeys with his parents, that he visited many countries and became acquainted with all those who at the time enjoyed a great reputation as philosophers, among whom the most illustrious were Ammonius Saccas, Origen the Pagan, Plotinus, and Amelius.
The few fragments of his commentaries which have come down to us show that he was free from the allegorical notions by which his contemporaries claimed to have discovered the wisdom of the ancients.
[4] In opposition to Plotinus, Longinus upheld the doctrine that the Platonic ideas existed outside the divine Nous.
At Athens, Longinus seems to have lectured on philosophy and criticism, as well as on rhetoric and grammar,[6] and the extent of his knowledge was so great, that Eunapius calls him "a living library" and "a walking museum;".
[8] After having spent much of his life at Athens composing the best of his works, he went to the East, either to see his friends at Emesa or to settle some family affairs.
She availed herself of the advice of Longinus; it was he who advised and encouraged her to shake off Roman rule and become an independent sovereign.
[13] Notwithstanding his many avocations, Longinus composed a great number of works, which appear to have been held in the highest estimation, all of which have perished.