The distinction between act and potency has an immediate consequence, which one can try to ignore but cannot suppress without ruining everything that precedes:

What is in potency cannot actualize itself.

This is not a theological thesis. It is not an arbitrary metaphysical postulate. It is a direct logical requirement.

For indeed, if a thing is in potency with respect to a given determination, this precisely means that it does not yet possess it. To say that it could give itself what it does not yet have is to say that it already has it. It is a pure and simple contradiction.

In other words: what is only capable of being otherwise is not yet what it becomes. It therefore needs a principle already in act to be actualized.

Why self-actualization is impossible

To suppose that a thing can actualize itself amounts to affirming that it is, under the same respect:

• in potency (since it must change),
• and in act (since it would produce this change).

This is exactly what the principle of non-contradiction forbids.

This point is often masked by vague formulations: one speaks of "spontaneity," "natural process," "emergence." But these words explain nothing. They rename the problem without solving it.

Spontaneity is not the absence of cause; a process is always the process of something; emergence already presupposes actual conditions from which something emerges.

Language can be inventive. Reality remains stubborn.

Accidental causality and hierarchical causality

At this stage, a decisive distinction imposes itself.

There are accidental causal series, where causes succeed one another in time:

• a father begets a son,
• the son in turn begets another son,
• the first can die without the series collapsing.

These series can, in principle, be long, even indefinite. They do not pose the real metaphysical problem.

But there are also hierarchical causal series, where causes are not simply prior in time, but simultaneously dependent:

• the hand moves the stick,
• the stick moves the stone.

If the hand ceases to act, the stick no longer acts, and the stone no longer moves. Causality here is actual, not inherited.

It is this second type of causality that is decisive.

Down to earth: why hierarchy is inescapable

Let us take simple examples.

First example: the instrument. An instrument only acts insofar as it is used. A knife does not cut by itself. It cuts because an agent employs it. Its capacity to act is real, but derived. It depends on a first act.

Second example: movement. A wagon is pulled by a locomotive. The force it exerts does not belong to it properly; it is transmitted. If there is no actual source of movement, the whole chain stops.

Third example: natural processes. To say that a process "happens by itself" only means that it is not intentionally directed by a human agent. It never means that it is without an actual principle. Nature is not an active nothingness.

In all cases, the same structure appears: what acts without being in act by itself acts by participation.

The actual dependence of becoming

Let us return to change.

At every instant when a thing changes, it passes from potency to act. And at every instant, this passage requires a principle already in act. Not yesterday. Not in a distant past. Here and now.

In other words: the becoming of reality is actually suspended on actualizing principles.

One can multiply the mediations, the levels, the relays—but one cannot suppress this dependence without abolishing change itself.

And here is where the metaphysical import becomes impossible to evade.

The consequence that is always postponed

If everything that changes is actualized by something else, and if this actualization is hierarchical and actual, then a question imposes itself, whether one likes it or not:

Can one have a hierarchical series of actualization without a first term in act?

A series where everything would be instrument, but where nothing would be source. A series where everything would be borrowed, but where nothing would be possessed in its own right.

The answer is not difficult. Such a series would not act at all.

If everything is derived, nothing is given. If everything is in potency with respect to its acting, nothing acts.

At this stage, it becomes clear that reality, as we experience it—changing, structured, intelligible—cannot be ultimately self-sufficient.

And without yet naming what this implies, one thing is now certain: the becoming of the world presupposes a principle that is not itself in becoming.

What follows is no longer an option. It is a necessity.