But if absolutely nothing can be said about the One, why call it “the One”?

This is an even better objection.

The answer is that “the One” isn't supposed to be a normal description of the One.

When Proclus says:

“The One”

he isn't saying:

“I have discovered an object which possesses the property of being one.”

He's using One to indicate what we encounter when we try to think beyond multiplicity altogether.

Imagine asking:

What's the most fundamental thing?

You might say:

matter.

Proclus says: matter is already multiple — it has parts, properties, boundaries, change, etc.

So maybe:

being.

But being is also already a distinction: this is rather than that isn't.

So Proclus keeps stripping things away:

physical things → soul → intellect → being → ???

And eventually he says: beyond all of these is absolute unity.

But—and this is crucial—absolute unity cannot be an ordinary “thing.”

Because the moment you say:

“The One has property X”

you've introduced a distinction between the One and X.

You've made the One into something with components or characteristics.

So “One” is partly a negative/limit concept. It's saying:

“We're pointing toward that which isn't divided into anything else.”

Not:

“Here is an object called The One, and its defining feature is the number 1.”

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And this creates the famous paradox

You're essentially asking:

If you can't say what the One is, how can you possibly know that it exists or that it causes anything?

Exactly.

Proclus' answer is that we don't know the One in the same way we know ordinary objects.

We know things about ordinary objects.

For example:

“Socrates is human.”

But with the One, Proclus thinks our intellect eventually reaches a point where positive descriptions break down.

So we approach it by negation:

• not multiple
• not material
• not changing
• not being
• not intellect
• not a particular thing

This is called apophatic theology or negative theology.

And then there is a further step: intellectual/mystical union, where the claim is that the soul can somehow become united with the One rather than merely forming a proposition about it.

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There's an important distinction here

Proclus is not saying:

“The One is a mysterious object that happens to have no describable properties.”

He's saying something much stranger:

The One is prior to the distinction between an object and its properties in the first place.

That's why he thinks ordinary language keeps failing.

And that's also why you shouldn't imagine his hierarchy as:

One → giant cosmic machine → universe

It's more like:

absolute unity → multiplicity → increasingly determinate forms of reality

The entire metaphysical problem he's wrestling with is:

How do you get multiplicity without putting multiplicity into the ultimate principle?

That's the engine driving a huge amount of Neoplatonism.

And honestly, whether Proclus actually succeeds is a completely legitimate question. You can argue that saying “the One causes everything but doesn't act, choose, change, or even possess being” is less an explanation and more a sophisticated way of restating the mystery.

That criticism gets very interesting when you compare Plotinus, Proclus, and Aristotle.