Ackrill  has pointed out that Aristotle ’s criterion concerning incompleteness ought to classify walking a mile and hearing a symphony as kineseis, not complete until the end, whereas engaging in walking or in listening to music, being complete at any stage, should be energeiai. Thus in effect Aristotle has succeeded in distinguishing descriptions of what is going on, rather than, as he intended, types of thing going on. Nonetheless, such a distinction could in fact have been very useful, say, to a Stoic philosopher who recommends living every hour as if your last, and pinning no hopes on the future. This attitude requires you to be concerned with certain descriptions of what you are doing, with ‘composing music’ rather than with ‘composing a symphony’, since the latter may never get completed.
Plotinus 6.1  16 wants a very different account of change as not contrasted with energeia, but a species of it. Moreover, he wants change to be a timeless relation among timeless intelligible entities. To achieve this result, he here seizes on Aristotle ’s failure to see that it is not walking, but walking a certain distance that is incomplete.
Plotinus also exploits some of Aristotle ’s remarks about instantaneity, even though he himself wants change to be timeless in a stronger sense of being altogether outside of time, not merely instantaneous. Aristotle had pointed out that some energeiai can be instantaneous, EN 1174b7. Perhaps thoughts would be an example, but this is not a characteristic of all energeiai. Another thing that can be instantaneous for Aristotle is having completed a change, such as a pond’s having frozen over all at one go (athroon), Phys. 1.3, 186a15-16; Sens. 7, 446b28-447a6. Plotinus seizes on this in 6.1  16 (33-7), to argue that change is timeless in his  different sense, without noticing that Aristotle is talking about having changed, not about changing.
Aristotle does, however, invite misunderstanding, in three passages in his discussion of change (kinesis) in Physics 3, chapters 1-3. He there contrasts ener-geia (and equivalently entelekheia) with dunamis, as an actualisation as opposed to a potentiality awaiting actualisation. In this usage, kinesis, so far from being contrasted with energeia, can actually be an energeia. For example, in one of the three passages, Phys. 3.3, 202a22-b22, Aristotle describes the energeia (activity or actualisation) of a teacher as being a kinesis, which is located not in the teacher, but in the learner. Plotinus exploits this use of energeia for the kinesis of teaching, when in 6.3  23 (6-22) he talks of causing your feet to walk. But confusingly, Plotinus speaks of this as a kinesis which comes to be energeia and resides in your feet.