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to mystic institute.org. Today I'm going to be talking about Aquinas on the identity

of essence and existence in God. Aquinas, as you may have heard, accepts the doctrine of divine simplicity.

Divine simplicity, as you also may have heard, can be thought of roughly, very roughly,

as divine non-complexity. God isn't complex.

But what is complex?

Complexity means having a multiplicity of components or parts or constituents. So, for example, I have two arms and two legs, which means that I have a multiplicity

of parts. So therefore, I am complex. So therefore I am at least in that respect not simple. But God has

no physical parts, so therefore he is at least in that respect simple. That is not complex.

Twice now I've said in that respect.

It's important to realize that something can be simple in one respect, but complex in another.

Angels, for example, are simple in the sense that they don't have a multiplicity of physical parts,

which is obvious enough in as much as they aren't physical at all.

But in another sense, at least from Aquinas' perspective, angels are complex.

For instance, there is a difference between an angel's nature and its various acts of understanding.

So if someone asks whether something is complex or not, it's usually a good

idea to ask, in what respect? Sometimes, in a particular argumentative context, it may be enough

for Aquinas or for us to establish only that God is simple in a certain respect.

For example, a particular argument may require only that God lack physical parts.

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