Before the 3rd century you're having several philosophical schools still as a going concern. You have not only the Platonists and the Aristotelians but you have Scepticism, you have Stoicism, you even have a little bit of Epicureanism. And what happens after Plotinus is that everybody becomes a Neo-Platonist. So if we then go forward to the Islamic world for example, Plotinus is immensely influential, and Neo-Platonism becomes at least one major component of mainstream Islamic philosophy as well.

People often talk about Plotinus' system. The reason they do this is that Plotinus postulated a kind of series or chain of principles, so at the top there's what he called the One. Below the One is what he called Intellect. Below Intellect is Soul, and the effect of the soul is the physical world that we actually live in.

The forms in intellect are some kind of blueprint or model on which the physical world is based, and something needs to come along and shape the matter in accordance with that blueprint. What does that is soul.

We do each have an intellect but there's a universal intellect which is the same for everybody, as it were. And this single intellect is grasping the platonic forms.

There's going to be this realm of Platonic forms and then there's going to be this single mind, the 'nous', which grasps them.

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.

Who you really are, is an immaterial soul and the body is an external thing that's sort of an encrustation your soul. So this has important implications for Plotinus' ethics, because his ethics are basically all about encouraging us to turn away from the body and turn towards these higher principles, so universal soul, universal intellect and ultimately the One.