Porphyry on Plotinus. Ennead I - Loeb Classical Library 2 Revised edition

Plotinus was the first and greatest of Neoplatonic philosophers. His writings were edited by his disciple Porphyry, who published them sometime between AD 301 and 305 in six sets of nine treatises each (Enneads), with a biography of his master in which he also explains his editorial principles.