The soul must be distinct from intellect because even at its best, what the soul does when it's thinking, is it thinks linguistically, it thinks in a temporarily extended way, so it for example, might go through the steps of an argument chain, as if you were going through a syllogism and seeing that something followed from the premises, whereas intellect simply grasps the forms.

The body is some kind of image of you, it's kind of something that's just attached to your soul, some kind of outside principle, which doesn't really represent who you really are.

If you think about even very common examples like, say, something that you would build, like a clock or a car or a group of people trying to accomplish something, it fails when its unity breaks down. So when it stops having a single form, which is functioning all together, then it sort of falls apart into discrete elements.

Just the way you might look at a painting and see the painting, and the painting is outside you, so this immaterial intellect would see the forms and behold them, as if they were standing before it. And Plotinus said that that can't be right because it falls prey to sceptical objections.

Basically the problem is that if the intellect is looking at or beholding the forms, what it will get is some kind of representation or image of the forms, but it won't actually have the forms, it won't touch them as it were, or it won't incorporate them.

This condition of uncertainty and unrest in the Roman Empire might explain why at Plotinus' philosophy encourages us to sort of flee from the physical world and towards the world of ideas.

The importance of Plotinus is not only his own philosophical ideas which are quite interesting, but his historical impact as the founder of neo-Platonism which is the main philosophical tradition of late antiquity.