Plotinus (ca. 205-270) is widely considered the father of Neoplatonism. Much of our biographical information about Plotinus comes from Porphyry's preface to his edition of Plotinus' Enneads.
Porphyry believed Plotinus was sixty-six years old when he died in the second year of the reign of the emperor Claudius II, and estimated the year of his teacher's birth as around 205. Plotinus disliked "being in the body", so he never discussed his ancestry, or his place or date of birth. Eunapius however reports that he was born in Lyco or Lycopolis in Egypt.
He took up the study of Philosophy at the age of twenty-seven, around the year 232, and went to Alexandria to study. Plotinus was dissatisfied with every teacher he met until a friend suggested he go to Ammonius Saccas. Upon hearing Ammonius lecture, he declared to his friend, "this was the man I was looking for," and began to study intently under this teacher. Plotinus spent the next eleven years in Alexandria until his 38th year, when he decided to investigate the philosophical teachings of the Persians and the Indians. As a result he left Alexandria and joined the army of Gordian III as it marched on Persia. However, on Gordian's death he found himself abandoned in a hostile land, and with difficulty found his way back to safety in Antioch.
At the age of forty, during the reign of Philip the Arab, he came to Rome, where he lived for most of the remainder of his life. He attracted a number of students in that city. His innermost circle included Porphyry, Gentilianus Amelius of Tuscany, the Senator Castricius Firmus, and Eustochius of Alexandria- a doctor who devoted himself to learning from Plotinus and attended to him until his death.
Others included: Zethos, an Arab by ancestry who died before Plotinus and left him a legacy and some land; Zoticus, a critic and poet; Paulinus, a doctor of Scythopolis; and Serapion from Alexandria. He had students amongst the Roman Senate beside Castricius, such as Marcellus Orontius, Sabinillus, and Rogantianus. Women were also numbered amongst his students, including Gemina, in whose house he lived during his residence in Rome, and her daughter Gemina; and Amphiclea, the wife of Ariston the son of Iamblichus. He was a correspondent of the philosopher Cassius Longinus.
He also had the respect of the Emperor Gallienus and his wife Salonica. At one point Plotinus attempted to interest Gallienus in rebuilding an abandoned settlement in Campania known as the City of Philosophers, where the inhabitants would live under the constitution set out in Plato's Laws. The support of an Imperial subsidy did not come to pass due to reasons Porphyry did not know, and the settlement never happened.
After Porphyry went to live in Sicily, word came to him that Plotinus had died. The philosopher spent his final days in seclusion on an estate in Campania which his friend Zethos had bequeathed him. According to the account of Eustochius, who attended upon him at the end, Plotinus' final words were: "Strive to give back the Divine in yourselves to the Divine in the All." At that moment a snake crept under the bed where Plotinus lay, and slipped away through a hole in the wall; at the same moment Plotinus died.
Besides Ammonius, Plotinus was greatly influenced by the works of Alexander of Aphrodisias and Numenius.
Porphyry wrote the essays that became the Enneads over a period of years, from ca. 253 to a few months before his death. Plotinus was unable to revise his own work due to his poor eyesight. Yet his writings badly needed editing, according to Porphyry: Plotinus' handwriting was atrocious, he did not properly separate his words, and he cared nothing for spelling. He disliked the process of rewriting them, so he gave the task to Porphyry, who not only polished them but put them into the arrangement we now have.
Although Plotinus attacked Gnosticism, he was silent about Christianity, of which he must have been aware. From all accounts his personal and social life exhibited the highest moral and spiritual standards.
The One contains no division, multiplicity or distinction. Compare, for example, Advaita Vedanta, ("advaita" = "not two", or "non-dual"). Thus, no attributes can be assigned to the One. Thought cannot be attributed to the One because thought implies distinction between a thinker and an object of thought. Likewise, neither will nor activity can be ascribed to the One, since doing so would logically require distinction between an "Agent" of will or act, and its object.
The One, beyond all attributes, including being and non-being, is the source of the world not through any act of creation, willful or otherwise, since activity cannot be ascribed to the unchangeable, immutable One. Plotinus resorts to a logical principle that the "less perfect" must, of necessity, "emanate", or issue forth, from the "perfect" or "more perfect". Thus, all of "creation" emanates from the One in succeeding (not temporal) stages of lesser and lesser perfection.
Plotinus offers an alternative to the orthodox Christian notion of creation ex nihilo (out of nothing), which would make God suffer the deliberations of a mind and actions of a will. Emanation ex deo (out of God), confirms the absolute transcendence of the One making the unfolding of the cosmos purely a consequence of the existence of the One. The One is in no way affected or diminished by the emanations. The One does not divide itself into multitudes of lesser beings, or parcel himself out piece by piece. Plotinus uses the analogy of the Sun which emanates light indiscriminately without thereby "lessening" itself, or a mirror reflection which in no way diminishes the object reflected.
The first emanation is Thought (Nous), identified with the "demiurge" in Plato's Timaeus. From Nous proceeds the "World Soul", which Plotinus divides into "upper" and "lower", identifying the lower with Nature. From the World Soul proceed individual Human souls, and finally, matter, at the lowest level of being and Perfection.
Although the "material world" is at the lowest level of the "chain of being", Plotinus criticized the Gnostic disdain for matter. Plotinus asserted the ultimately divine nature of material creation since it is the product of Nous (the demiurge) and the World Soul.
The essentially religious nature of Plotinus' philosophy may be further illustrated by his concept of attaining "ecstatic" union with the One. Porphyry relates that Plotinus achieved "union" several times during the years he knew him. Compare, of course, "enlightenment", "Liberation", and other concepts of mystical union common to many Eastern and Western traditions.
Neoplatonism was sometimes used as a philosophical foundation for Paganism, and as a means of defending paganism against Christianity; but many Christians were also influenced by Neoplatonism. The teachings of Plotinus influenced many of the early Christian Fathers, e.g., St. Augustine.
In the 20th century, American philosopher Ken Wilber has drawn heavily upon Plotinus in his Cosmology, reaching some similar Metaphysical conclusions.