As a very young man, I was deeply invested in a holistic, minimally unworldly reading of Plotinus. At the time, I was impressed by his view of Intellect (nous) as a sort of synoptic rational intuition or vision. I liked his (actually Aristotelian) view that the good of any being is its natural act, which leaves it to us to determine what that actually is. I read the One as the All viewed sub specie aeternitatis (“under the form of eternity”, in Spinoza’s later phrase). I was fascinated by so-called “emanation” or “procession”, which obscurely suggested a sort of rational unfolding into detail from a more purely holistic starting point.
Plotinus was a 3rd century CE Alexandrian Greek who founded the so-called “neoplatonic” school that came to dominate philosophy and theology in late antiquity. He combined Platonic, Aristotelian, and various religious influences. His work The Enneads was a major inspiration to the greatest early Catholic thinker Augustine, and part of it was later translated to Arabic and Latin under the misleading title Theology of Aristotle. Plotinus associated the Good of Plato’s Republic with the One of Plato’s Parmenides.
Too briefly, one might say that for Plotinus and the neoplatonists generally, the One unfolds into the One-Many of Intellect, which unfolds into the Many-One of Soul, which unfolds into the Many of nature, and then it all re-folds back into itself, forming a big eternally repeating M.C. Escher loop. To say it in a more Aristotelian way, in that loop, what would be an Aristotelian unmoved mover and “first” cause that is really an end — along with everything it attracts — gets folded back into itself, making it literally also the beginning and the complete cause of everything, unlike anything in Aristotle. (As a youth who enjoyed mixing things up, I liked to imagine that the big Escher loop was also Nietzsche’s eternal return.)
Soul for Plotinus has no inherent dependency on the body — all the dependency at least ought to run in the other direction. Soul “There” seems to have connotations of simple immediate enjoyment of the intelligible realm, but “Here” is agitated and disturbed. He suggested a model of meditative discipline in which higher principles should detach themselves from immersive involvement in the layer beneath, but function as unmoved movers for it, leaving the lower layer to function autonomously except for the unmoved-mover influence of the higher layer.
He made an interesting suggestion that each Platonic form in a way includes all the others.
Neoplatonism is finally getting better treatment from scholars these days. 19th and 20th century summary accounts often reflected little acquaintance with texts, and were full of hostile stereotypes. Even the name is now considered misleading. The Stanford Encyclopedia of Philosophy article on the web is a decent starting point, though it anachronistically talks about “Consciousness”. (In fact, that English term was coined by Cambridge Platonist Ralph Cudworth in the 17th century for use in his translations of Plotinus. But in my opinion, the word has far too many modern connotations to be a good choice for historical scholarship. While such anachronism is expected in Hegelian/Brandomian recollective genealogy, that is because such genealogy serves different purposes from historical scholarship.)
The single most impressive study I’ve seen in English is Kevin Corrigan’s Plotinus’ Theory of Matter-Evil and the Question of Substance: Plato, Aristotle, and Alexander of Aphrodisias, which addresses a broader scope than the title suggests, while tackling Plotinus’ most apparently objectionable thesis head-on. (While Plotinus idiosyncratically identified Alexander’s abstract prime matter with evil due to its complete lack of form, he strongly defended the goodness of the manifestation of the physical world that includes ordinary matter against the Gnostics.) Corrigan’s book is especially interesting because it highlights an abundance of implicit dialogue with Aristotle and Alexander — unnoticed by previous scholars — in Plotinus’ texts that contributes substantially to the Plotinian synthesis.
In French, there is a very good treatment of the differences between Aristotle and Plotinus from an Aristotelian point of view: Gwenaëlle Aubry’s Dieu sans la puissance: dunamis et energeia chez Aristote et Plotin. (Neither Plotinus nor Aristotle sees any temporal origin of the world or beginning of time. The key difference is that Aristotle’s “First” cause is also not supposed to be any kind of eternal origin either. It is purely that which everything ultimately aims at, a “final cause”. For Plotinus, by contrast, the One is simultaneously that which everything aims at and the eternal origin of everything.) Aubry takes as a starting point Aristotle’s notion that the “First” cause is just pure actuality, with no admixture of the power Plato talks about, let alone the Stoic-inflected omnipotence averred by Plotinus (or the even stronger unconditional counterfactual omnipotence claimed by Philo of Alexandria and later theological voluntarists).
Nowadays my sympathies are entirely on the Aristotelian side, but Plotinus is still an important figure worthy of serious attention — in his own right; as a reader of Aristotle; and as an important influence on later neoplatonically inflected Aristotelianisms as well as later Platonisms. (See also Power of the One?)