Plotinus founded Neoplatonism, developing in the "Enneads" - compiled and edited by his student Porphyry - a systematic emanationist metaphysics in which the ineffable, transcendent "One" gives rise to Intellect (Nous, containing the Platonic Forms), which in turn gives rise to Soul, with the material world as the lowest, most diffuse level of reality. He held that the philosophical and mystical task of the soul is to "return" (epistrophē) toward the One through progressive contemplation, culminating in a non-discursive mystical union (henōsis).
Intellectual setting
Plotinus taught in Rome during the political instability of the mid-third century Roman Empire, attracting a circle of students including Porphyry, who both edited his scattered treatises into the "Enneads" after his death and wrote his biography.
Key ideas
Emanation from the One
Plotinus argued that all reality proceeds in a hierarchical series of emanations from the ineffable One - beyond being and description - through Intellect and Soul down to matter, with each level dependent on, but distinct from, the level above it.
The soul's return and mystical union
Plotinus held that the philosophical life is fundamentally a turning back (epistrophē) of the soul toward its source in the One, achieved through progressive contemplative purification and culminating in a non-discursive mystical union (henōsis) beyond ordinary thought.
Legacy
Plotinus's Neoplatonism became one of the most influential philosophical systems of late antiquity, decisively shaping Christian theology through Augustine and Pseudo-Dionysius, Islamic Neoplatonism, and the later history of Western mysticism and metaphysics.