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.

I think it's important to realise that what happens in Neo-Platonism beginning with Plotinus and Porphyry and then going on for the next several centuries, is a real kind of contest for the ideas and convictions of the intelligentsia of the later Roman Empire. So that you have Christians slowly converting more and more powerful people until of course actually Constantine and then other emperors after him, become Christian, and the empire becomes a Christian empire rather than Pagan empire.

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 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.

There's a stronger and more kind of controversial element of Plotinus' view of matter, which is that he actually identifies it with evil, or at least the principle of evil, and the reason for this is that he thinks that the the One, the highest principle, can also be thought of as the Good, and that's kind of surprising like, because he has this negative theology which doesn't allow us to say anything about the One. But he believes that it can be seen as the principle of goodness as well as unity, and that if you think about it, goodness and unity sort of go along with each other.

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.

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.