Actuality (Existence) is prior to potentiality (Change)

Actuality, or actual existence, is prior to potentiality.

Potentiality, or possibility of change, is that definite kind which is a principle of change in a thing.

• It is every principle of movement or rest.

Nature also is in the same genus as potency or the possibility of change.

• It is a principle of movement of the thing itself.

To all such possibility of change, then, actuality is prior both in cause-and-effect formula and in substantiality. In terms of time or temporal perception, actual existence is prior in one sense, but not in another.

1. Actual Existence is prior in cause-and-effect formula.

That which has the possibility of change [is potential] in the primary sense is potential because it is possible for it to become active.

For example:

• ‘capable of building’ is something that can build.
• ‘capable of seeing’ is something that can see.
• ‘visible’ is something that can be seen.

The same account applies to all other cases, so that the cause-and-effect formula and the knowledge of its existence precedes the knowledge of its possible changes.

2. In terms of time or temporal sequence, the possibility of change is prior

The future actual thing is identical in species, but not in number with a current thing that has the possibility of change.

A man now exists here actually, along with a corn seed.

• But that actuality is not yet real until the man has seen the corn.

• Until then, the man and corn are potentialities.

• This is how potency is prior to actuality.

From the potentially existing, the actual existence is always produced by an actually-existing thing, e.g. man from man, musician by musician.

There is always a first mover. The mover already actually exists.

We have said in our account of substance that everything that is produced is something produced:

• from something and
• by something

That something is the same in species as it.

This is why it is thought impossible:

• to be a builder if one has built nothing
• to be a harper if one has never played the harp

He who learns to play the harp learns to play it by playing it. All other learners do similarly.

A sophistical quibble arises from this.

One who does not know a science will be learning the object of the science. This is because a learner still has no knowledge of what he is learning.

But that which is coming to be must have some part existing. That which is changing, in general, must have some part changed (this is shown in the treatise on movement). Then it follows that he who is learning must know some part of the science.

But here too, it is clear that actuality is in this sense also – it is prior to potency in terms of the order of generation and of time.

3. Potentiality, or possibility of change, is also prior in substantiality

(a) This is because the things that are posterior in becoming are prior:

• in form and
• in substantiality

For example:

• man is prior to boy
  • Man already has its form, but the boy has not
• human being is prior to seed.
  • Human being already has its form, but the seed has not

Everything that comes to be moves towards a principle or an end.

• A thing’s principle is its reason for existing.
• Its existence is for the sake of that principle.

Its actuality is the goal. The thing acquires potency for the sake of this actuality.

Animals do not see so that that they may have sight.

• Instead, they have sight so that they may see.

Similarly, men have:

• the art of building so that they may build
• theoretical science so that they may theorize

But men do not theorize so that they may have theoretical science, except those who are learning by practice.

• Those learners-by-practice do not theorize except in a limited sense, or because they have no need to theorize.

Matter exists in a potential state just because it can exist in its form. When it exists actually, then it is in its form. This holds good in all cases, even those in which the end is a movement.

Teachers have achieved their end when they have exhibited to the pupil.

Nature does likewise.

If this is not the case, then we shall have Pauson’s Hermes over again. This is because it will be hard to say whether the knowledge was within or without, like the shape in a picture.

The action is the end. The actuality is the action.

And so even the word ‘actuality’ is derived from ‘action’, and points to the complete reality.

In some cases, the exercise is the ultimate thing. For example: in sight, the ultimate thing is seeing.

But from some things, a product follows. For example, from the art of building results:

• a house
• the act of building

Yet in the former case, the act is the end.

• In the latter, the act is more of an end than the potency is.

The act of building is realized in the thing that is being built.

• It exists at the same time as the house.

It shows that:

• the result is different from the exercise
• the actuality is in the thing that is being made.

For example:

• The act of building is in the thing that is being built
• The act of weaving is in the thing that is being woven

In general, the movement is in the thing that is being moved.

But where there is no product apart from the actuality, the actuality is present in the agents.

For example, the act of seeing is in the seeing subject. The act of theorizing is in the theorizing subject. The life and well-being are in the soul (well-being is a certain kind of life).

Obviously, the substance or form is actuality.

Actuality is prior in substantial being to potency.

One actuality always precedes another in time right back to the actuality of the eternal prime mover.

But (b) actuality is prior in a stricter sense also.

Eternal things are prior in substance to perishable things.

No eternal thing exists potentially because every potentiality is at one and the same time a potentiality of the opposite. While that which is not capable of being present in a subject cannot be present, everything that is capable of being may possibly not be actual.

That which is capable of existing may either exist or not exist.

The same thing is capable both of being and of not being.

That which is capable of not being may possibly not be; and that which may possibly not be is perishable, either in the full sense, or in the precise sense in which it is said that it possibly may not be, i.e. in respect either of place or of quantity or quality; ‘in the full sense’ means ‘in respect of substance’.

Nothing which is in the full sense imperishable is in the full sense potentially existent (though there is nothing to prevent its being so in some respect, e.g. potentially of a certain quality or in a certain place); all imperishable things, then, exist actually.

Nor can anything which is of necessity exist potentially; yet these things are primary; for if these did not exist, nothing would exist.

Nor does eternal movement, if there be such, exist potentially; and, if there is an eternal mobile, it is not in motion in virtue of a potentiality, except in respect of ‘whence’ and ‘whither’ (there is nothing to prevent its having matter which makes it capable of movement in various directions).

And so the sun and the stars and the whole heaven are ever active. There is no fear that they may sometime stand still, as the natural philosophers fear they may.

Nor do they tire in this activity, for movement is not for them, as it is for perishable things, connected with the potentiality for opposites, so that the continuity of the movement should be laborious; for it is that kind of substance which is matter and potency, not actuality, that causes this.

Imperishable things are imitated by those that are involved in change, e.g. earth and fire.

• These are ever active
• They move by themselves and in themselves.

But the other potentialities are all potentialities for opposites.

That which can move another in this way can also move it not in this way, i.e. if it acts according to a rational formula; and the same non-rational potencies will produce opposite results by their presence or absence.

The dialecticians say that the Ideas are entities or substances.

If they exist, then there must be something much more scientific than science. There must be something more mobile than movement itself.

These will be more of the nature of actualities, while science-itself and movement-itself are potencies for these.

Obviously, then, actuality is prior both to potential and to every principle of change.