Plotinus had an inherent distrust of materiality (an attitude common to Platonism), holding to the view that phenomena were a poor image or mimicry (mimesis) of something "higher and intelligible" [VI.I] which was the "truer part of genuine Being". This distrust extended to the body, including his own; it is reported by Porphyry that at one point he refused to have his portrait painted, presumably for much the same reasons of dislike. Likewise Plotinus never discussed his ancestry, childhood, or his place or date of birth. From all accounts his personal and social life exhibited the highest moral and spiritual standards.
Plotinus took up the study of philosophy at the age of twenty-seven, around the year 232, and travelled to Alexandria to study. There Plotinus was dissatisfied with every teacher he encountered until an acquaintance suggested he listen to the ideas of 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 his new instructor. Besides Ammonius, Plotinus was also influenced by the works of Alexander of Aphrodisias, Numenius, and various Stoics.
After spending the next eleven years in Alexandria, he then decided to investigate the philosophical teachings of the Persian philosophers and the Indian philosophers around the age of 38. In the pursuit of this endeavour he left Alexandria and joined the army of Gordian III as it marched on Persia. However, the campaign was a failure, and on Gordian's eventual death Plotinus found himself abandoned in a hostile land, and only 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 stayed for most of the remainder of his life. There he attracted a number of students. His innermost circle included Porphyry, Amelius Gentilianus 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. Other students included: Zethos, an Arab by ancestry who died before Plotinus, leaving 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, also Gemina; and Amphiclea, the wife of Ariston the son of Iamblichus. Finally, Plotinus was a correspondent of the philosopher Cassius Longinus.
While in Rome Plotinus also gained the respect of the Emperor Gallienus and his wife Salonina. 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. An Imperial subsidy was never granted, for reasons unknown to Porphyry, who reports the incident.
Porphyry subsequently went to live in Sicily, where word reached him that his former teacher 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 him at the end, Plotinus' final words were: "Strive to give back the Divine in yourselves to the Divine in the All." Eustochius records that a snake crept under the bed where Plotinus lay, and slipped away through a hole in the wall; at the same moment the philosopher died.
Plotinus wrote the essays that became the Enneads over a period of several years from ca. 253 until a few months before his death seventeen years later. Porphyry makes note that the Enneads, before being compiled and arranged by himself, were merely the enormous collection of notes and essays which Plotinus used in his lectures and debates, rather than a formal book. Plotinus was unable to revise his own work due to his poor eyesight, yet his writings required extensive editing, according to Porphyry: his master's handwriting was atrocious, he did not properly separate his words, and he cared little for niceties of spelling. Plotinus intensely disliked the editorial process, and turned the task to Porphyry, who not only polished them but put them into the arrangement we now have.
For example, thought cannot be attributed to the One because thought implies distinction between a thinker and an object of thought. Even the self-contemplating intelligence must contain duality. "Once you have uttered 'The Good,' add no further thought: by any addition, and in proportion to that addition, you introduce a deficiency." [III.8.10] Plotinus denies sentience, self-awareness or any other action to the One [V.6.6], rather if we insist on describing it further we must call the One a sheer Dynamis or potentiality without which nothing could exist. [III.8.10] As Plotinus explains in both places and elsewhere [e.g. V.6.3], it is impossible for the One to be Being or a self-aware Creator God. At [V.6.4], Plotinus compared the One to "light", the Divine Nous (first will towards Good) to the "Sun", and lastly the Soul to the "Moon" whose light is merely a "derivative conglomeration of light from the 'Sun'". The first light could exist without any celestial body.
The One, being beyond all attributes including being and non-being, is the source of the world -- but not through any act of creation, willful or otherwise, since activity cannot be ascribed to the unchangeable, immutable One. Plotinus argues instead that the multiple cannot exist without the simple. 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 stages of lesser and lesser perfection. These stages are not temporally isolated, but occur throughout time as a constant process. Later Neoplatonic philosophers, especially Iamblichus, added hundreds of intermediate beings as emanations between the One and humanity; but Plotinus' system was much simpler in comparison.
Plotinus offers an alternative to the orthodox Christian notion of creation ex nihilo (out of nothing), which attributes to God the deliberation of mind and action of a will, although Plotinus never mentions Christianity in any of his works. Emanation ex deo (out of God), confirms the absolute transcendence of the One, making the unfolding of the cosmos purely a consequence of its existence; the One is in no way affected or diminished by these emanations. Though the emanations are, since as they become farther away from the source they became diminished. Plotinus uses the analogy of the Sun which emanates light indiscriminately without thereby diminishing itself, or reflection in a mirror which in no way diminishes or otherwise alters the object being reflected.
The first emanation is nous (thought or the divine mind, logos or order, reason), identified metaphorically with the demiurge in Plato's Timaeus. It is the first will towards Good. From nous proceeds the world soul, which Plotinus subdivides into upper and lower, identifying the lower aspect of Soul with nature. From the world soul proceeds individual human souls, and finally, matter, at the lowest level of being and thus the least perfected level of the cosmos. Despite this relatively pedestrian assessment of the material world, Plotinus asserted the ultimately divine nature of material creation since it ultimately derives from the One, through the mediums of nous and the world soul. It is by the Good or through beauty that we recognize the One, in material things and then in the Forms.
The essentially devotional nature of Plotinus' philosophy may be further illustrated by his concept of attaining ecstatic union with the One (henosis see Iamblichus). Porphyry relates that Plotinus attained such a union four times during the years he knew him. This may be related to enlightenment, liberation, and other concepts of mystical union common to many Eastern and Western traditions. Some have compared Plotinus' teachings to the Hindu school of Advaita Vedanta (advaita "not two", or "non-dual"),.
Authentic human happiness for Plotinus consists of the true human identifying with that which is the best in the universe. Because happiness is beyond anything physical, Plotinus stresses the point that worldly fortune does not control true human happiness, and thus “… there exists no single human being that does not either potentially or effectively possess this thing we hold to constitute happiness.” (Enneads I.4.4) The issue of happiness is one of Plotinus’ greatest imprints on Western thought, as he is one of the first to introduce the idea that eudaimonia (happiness) is attainable only within consciousness.
The true human is an incorporeal contemplative capacity of the soul, and superior to all things corporeal. It then follows that real human happiness is independent of the physical world. Real happiness is, instead, dependent on the metaphysical and authentic human being found in this highest capacity of Reason. “For man, and especially the Proficient, is not the Couplement of Soul and body: the proof is that man can be disengaged from the body and disdain its nominal goods.” (Enneads I.4.14) The human who has achieved happiness will not be bothered by sickness, discomfort, etc., as his focus is on the greatest things. Authentic human happiness is the utilization of the most authentically human capacity of contemplation. Even in daily, physical action, the flourishing human’s “…Act is determined by the higher phase of the Soul.” (Enneads III.4.6) Even in the most dramatic arguments Plotinus considers (if the Proficient is subject to extreme physical torture, for example), he concludes this only strengthens his claim of true happiness being metaphysical, as the truly happy human being would understand that that which is being tortured is merely a body, not the conscious self, and happiness could persist.
Plotinus offers a comprehensive description of his conception of a person who has achieved eudaimonia. “The perfect life” involves a man who commands reason and contemplation.(Enneads I.4.4) A happy person will not sway between happy and sad, as many of Plotinus’ contemporaries believed. Stoics, for example, question the ability of someone to be happy (presupposing happiness is contemplation) if they are mentally incapacitated or even asleep- Plotinus disregards this claim, as the soul and true human do not sleep or even exist in time, nor will a living human who has achieved eudaimonia suddenly stop using its greatest, most authentic capacity just because of the body’s discomfort in the physical realm. “…The Proficient’s will is set always and only inward.” (Enneads I.4.11)
Overall, happiness for Plotinus is "...a flight from this world's ways and things." (Theat 176AB) and a focus on the highest, i.e. Forms and The One.
Plotinus seems to be one of the first to argue against the still popular notion of causal Astrology. In the late tractate 2.3, "Are the stars causes?", Plotinus makes the argument that specific stars influencing one's fortune (a common hellenistic theme) attributes irrationality to a perfect universe, and eliminates moral turpitude. He does, however, claim the stars and planets are ensouled, as witnessed by their movement.
In the case of gnosticism it is important to understand that Plotinus and the Neoplatonists viewed it as a form of heresy or sectarianism to the Pythagorean and Platonic philosophy of the Mediterranean and Middle East. He accused them of using senseless jargon and being overly dramatic and insolent in their distortion of Plato's Ontology.
Plotinus attacks his opponents as untraditional, irrational and immoral and arrogant. He also attacks them as elitist and blasphemous to Plato for the Gnostics despising the material world and its maker.
Plotinus, for example, attacked the Gnostics for vilifying Plato's ontology of the universe contained in Timaeus, and the universes' creation by the demiurge. In this view the Demiurge is an artist or craftsman, in that he creates through mixing or amalgamating what already is. Plotinus accused Gnosticism of vilifing the Demiurge or craftsman that crafted the material world, even thinking of the material world as evil or a prison.
The Neoplatonic movement (though Plotinus would have simply referred to himself as a philosopher of Plato) seems to be motivated by the desire of Plotinus to revive the pagan philosophical tradition. Plotinus was not claiming to innovate with the Enneads, but to clarify aspects of the works of Plato that he considered misrepresented or misunderstood. Plotinus referred to tradition as a way to interpret Plato's intentions. Because the teachings of Plato were for members of the academy rather than the general public, it was easy for outsiders to misunderstand Plato's meaning. However, Plotinus attempted to clarify how the philosophers of the academy had not arrived at the same conclusions (such as misotheism or Dystheism of the creator God as an answer to the problem of evil) as the targets of his criticism.