With the Soul there is the beginning of time, and therefore of Creation (because Creation by its very nature requires sequence in which to occur). Whereas the Nous embraces the whole of the Noetic world in one timeless vision, the Soul's contemplation is forced to change from one thing to another.
The Soul thus constitutes the Nous projected into Time. Although still creative and spiritual, is no longer eternal, or perfect in its consciousness. It cannot see things in a holistic and all-embracing way, but only successively, imperfectly, moment by moment, in terms of past and future. In keeping with Greek thought generally, Plotinus refers to an original cosmic and therefore Divine World-Soul, which is the creator of the visible cosmos, and the individual, for example the human, soul.
The Stoics conceived of individual souls as parts of the World-Soul. For Plotinus in contrast, the World-Soul is herself an individual soul, albeit a very large one, whose body is the cosmos which she forms and administers. But both the individual and the World- souls are manifestations of the one Universal Soul. This is essentially the same as the monistic Hindu philosopher Shankara's statement that the individual soul or Jiva and Ishwara or God the creator and ruler of the universe are both the result of super-imposition or Maya over the one Absolute or Atman-Brahman 
As well as this "horizontal" division there is also a "vertical" one. Plotinus and his successors integrated the Platonic distinction between the rational and irrational souls with the Aristotlean distinction of vegetative, sentient (animal), and rational soul-levels. They thus postulated a whole range of levels of psychic consciousness.
Being an intuitive and inspirational rather than a systematic thinker, Plotinus sometimes divides the Soul into higher/rational and lower/irrational, and sometimes into three or even more levels, the various classifications often being contradictory with each other . Sometimes the rational soul as a whole is identified with the "unfallen" soul. Plotinus went so far as to say that the soul, as an "intelligible cosmos", contains not only all other soul-principles (or Logoi) but also the levels of Intelligence and the One, and is therefore able to attain any of those principles; an idea close to the Vedantic and Buddhist concept of Enlightenment or Liberation.
Plotinus' psychology is as follows:
This concept of "vertical psychology" was later to figure prominently in Kabbalah and Sufism, and is still with us (minus the higher or spiritual/noetic element) in the Freudian psychoanalytical distinction of Ego (= Rational Soul) and Id (= Irrational Soul). In modern Theosophy and Occultism also, this gradation appears as the distinction between the Mental and the Astral (or Emotional or Desire) bodies.
Sometimes Plotinus adds a further hypostasis, phusis or Nature, as the lowest projection of Soul and the dim consciousness within plants, between Soul and the Sensible World. The Theosophical version of this is the "etheric plane".
The Soul is the lowest hypostasis, the lowest irradiation of the Divine. Deficient as it is, it still retains a trace of the original on-tological authenticity or Spiritual-Being-ness of the higher principles. Below the Soul there is only non-conscious matter - hyle - which Plotinus equated with "non-being" and total deprivation. Plotinus describes Matter as "non-being", in view of its formlessness and utter unsubstantiality, although he denies that this means absolute non-existence 
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 R. T. Wallis, Neoplatonism, pp.73-4
 Ibid, pp.73-4.