The soul is the principle of life, and it's also something much closer to our own awareness and consciousness of our existence because fundamentally for Plotinus what we are is souls, we're not intellects.

If you think about for example, proportionality and beauty, things like that, these seem to be some kind of representations of a kind of unity.

Plato in his dialogue The Phaedo says that whereas sticks and stones are both equal and unequal, (so maybe what that means is that each stick is going to be equal to some other sticks and unequal to some other sticks, so equal to the stick on the left maybe but shorter than the stick on its right) the form of equal is going to be just equal, and it won't partake of inequality at all. And it will be the cause of equality in things that are equal, for example, equal sticks and stones.

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.

Soul puts the determination or forms or images of forms, into matter.

Once you're in a kind of revealed religious tradition, you wind up having to explain how the things said about God in the Bible or the Qur'an or whatever religious text you're dealing with, why these statements are true.

Plotinus thought that the entire world has a single soul. He also thought that each animal and plant and of course human, has an individual soul.