About Plotinus (from Wikipedia):
Plotinus (204/5 – 270) was a major Greek-speaking philosopher of the ancient world. In his philosophy, described in the Enneads, there are three principles: the One, the Intellect, and the Soul. His teacher was Ammonius Saccas, who was of the Platonic tradition. Historians of the 19th century invented the term Neoplatonism and applied it to Plotinus and his philosophy, which was influential in Late Antiquity. Much of the biographical information about Plotinus comes from Porphyry’s preface to his edition of Plotinus’ Enneads. His metaphysical writings have inspired centuries of Pagan, Islamic, Jewish, Christian, and Gnostic metaphysicians and mystics.