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.

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.

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.

Assuming there is an intellect, we're clearly not this universal intellect or we would know it. So that's one function of soul.

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.

This is in a way the most important thing about soul is that it's a kind of principle which mediates between the universal intellect and the material world.

Al-Ghazali is the most important philosophical theologian of classical Islam, and Moderation in Belief is among his most important works. It sets out al-Ghazali's Ash?arite theology with unusual clarity and provides important background for such well-known works as his autobiographical Deliverance from Error and his attack on Avicenna in The Incoherence of the Philosophers. This first English-language translation, with notes that bring out the argumentation and background of the work, is thus very much to be welcomed.