This little essay is a sort of appendix, or follow-up, to the early treatise 4.7 (no. 2 in Porphyry’s chronological list), On the Immortality of the Soul. Plotinus is concerned here to highlight the intermediate nature of soul, between the completely indivisible nature of Intellect and the entirely divisible nature of bodies. In this, he is, as elsewhere, provoked to thought by what he regards as the ‘riddling utterance’ of Plato at Timaeus 35A1–3, that the soul contains an element which is ‘divided about bodies’. To a certain extent, this essay looks forward to the fuller discussion in 6.4–5, where the same preoccupation exercises him.
The essay is placed first in the fourth Ennead by Porphyry himself, but Marsilio Ficino, the first modern editor of Plotinus, chose to place it second, after the little note which follows it, which explains the residual confusion in its numbering.
§1. The real nature of soul being a recapitulation of the latter chapters (9–14) of 4.7: soul is a divine and intelligible reality, intermediate between the intelligible realm proper, which is the ‘indivisible’ of Tim. 35A, and the physical realm, which is the ‘divisible’, it itself being indivisible of its own nature, but ‘divisible’ insofar as it is incorporated.
§2. A systematic analysis of the claims that the soul is divisible and that it is entirely indivisible, and refutations of both. In fact, the soul is both divisible and indivisible, ‘one and many’.