Plotinus was a major philosopher of the ancient world. In his system of theory there are the three principles: the One, the Intellect, and the Soul. His teacher was Ammonius Saccas and he is of the Platonic tradition. Historians of the 19th century invented the term Neoplatonism and applied it to him 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, Christian, Jewish, Islamic and Gnostic metaphysicians and mystics.