Q5 A6: Whether goodness is rightly divided into the virtuous, the useful and the pleasant?

Yes. Goodness is rightly divided into the virtuous, the useful and the pleasant because this division corresponds to the movement of appetite according to its proper formality.

Because of the form of the movement of appetite, goodness is predicated analogically:

1. chiefly of the virtuous (what is absolutely good as an end in itself)

2. then of the pleasant (a state of rest in the form of the end)

3. and lastly of the useful (what is relatively good as a means to an end)

Q5 A5: Whether the essence of goodness consists in mode, species and order?

Yes. The essence of goodness, so far as it consists in perfection, consists also in mode, species and order because perfection is manifested in the whole order of causality.

Mode refers to material or efficient causality.

Species refers to formal causality.

Order refers to final causality.

Note that Aquinas here is simply showing the compatibility of the Aristotelian doctrine of causality (as just discussed in Q5 A4) with what was then more traditional vocabulary (e.g., from Augustine) for discussing goodness.

Q5 A4: Whether goodness has the aspect of a final cause?

Yes, but while the idea of goodness implies the aspect of a final cause (because goodness is that which all things desire) the idea of goodness also presupposes the idea of an efficient cause, and also of a formal cause.

This may be seen from the order of causality:

In the thing causing:
1. final cause = goodness as end moves the agent to act
2. efficient cause = the action of the agent moving to form
3. formal cause = actualization of the form in the thing caused

In the thing caused:
4. formal cause = the form whereby the thing is an actual being
5. efficient cause = that perfection of the thing by which it can reproduce its form
6. final cause = goodness as the basic principle of the thing's perfection

Note RO1: Beauty properly belongs to the nature of a formal cause, because the cognitive faculty recognizes that beauty consists in due proportion.

Q5 A3: Whether every being is good?

Yes. Every being, as being, is good because all being, as being, has actuality.

Since every act implies some sort of perfection, any actual being is thus in some way perfect. And perfection implies desirability and goodness.

Q5 A2: Whether goodness is prior in idea to being?

No. In idea, being is prior to goodness because being is the proper object of the intellect.

The first thing conceived by the intellect is being, because everything is knowable only inasmuch as it is in actuality.

And nothing is good except being.

Q5 A1: Whether goodness differs really from being?

No. Goodness and being are really the same, and differ only in idea, because goodness signifies perfection which is desirable.

Being properly signifies that something actually is, and actuality properly correlates to potentiality.

Q4 A3: Whether any creature can be like God?

Yes. All created things, so far as they are beings, are like God (He who is the first and universal principle of all being) but solely according to analogy, inasmuch as God is essential being, whereas other things are beings by participation.

Although it may be admitted that creatures are in some way like God, it cannot be said that God is like creatures. This follows from the difference between a cause and that which is caused.

Q4 A2: Whether the perfections of all things are in God?

Yes. God does not lack whatever perfection anything else may have because He is the prior cause of that thing.

Also, He is the continuous cause sustaining all perfection in existence because He is ipsum esse per se subsistens ("being itself subsistent in itself"), which is what we established in Q3 A4 (viz., that God's existence and essence are the same).

Q4 A1: Whether God is perfect?

Yes. God is perfect because a thing is perfect in proportion to its state of actuality.

And God is Pure Act.

Q4: The perfection of God

We shall continue considering the essence of the one God by turning now from His simplicity (Q3) to His perfection.

And because everything in so far as it is perfect is called good, we shall have to address this difficulty by speaking of His goodness (Q6) -- and goodness in general (Q5) -- as well as His perfection (Q4).

Note that Aquinas also treats this difficult topic in his Exposition of the "On the Hebdomads" of Boethius.

We shall begin considering the pefection of God with three articles:

1. Is God perfect?
2. Is God perfect universally, as having in Himself the perfections of all things?
3. Can creatures be said to be like God?

Q3: The simplicity of God

Question 3 has established the absolute simplicity of God by answering eight articulations of the question:

1. Is God a body?
2. Is He composed of matter and form?
3. Is there composition of quiddity, essence or nature, and subject in Him?
4. Is He composed of essence and existence?
5. Is He composed of genus and difference?
6. Is He composed of subject and accident?
7. Is He in any way composite, or wholly simple?
8. Does He enter into composition with other things?

Q3 A8: Whether God enters into the composition of other things?

No. God is neither the form nor the matter of other things because He is the first cause whose actuality is primary and essential (i.e., He is the being of other things, but not their essence).

Note that Aquinas here, in a rare display of disgust, calls the theory of David of Dinant that God is prime matter the "most stupidly" formulated theory of all. (In the Latin: "qui stultissime posuit Deum esse materiam primam.")

The "most stupid" theory has it completely backwards: as if God were pure potentiality (viz., prime matter) rather than Pure Actuality!

Q3 A7: Whether God is altogether simple?

Yes. God is absolutely simple because He is in no way composite.

This follows from His being the Purely Actual, Uncaused, First, Absolute, Most Intelligent Being.

Benedict Ashley has a nice summary of the proof from motion (see Q2 A3) which allows us to establish, from empirical evidence, God's simplicity as Pure Act:

For a body to exist in motion, it must be moved by another actual mover. This actual mover is either:

(a) Itself an existent body that acts only because it too is being moved by another, or
(b) An existent mover that is not a body.

But an infinite series of movers such as posited in (a) is impossible because they would be only potential not actual movers.

Therefore, since bodies in motion are observed to exist, a First Unmoved Mover that is not a body must exist, and such an entity is what is meant in ordinary usage by the word “God”.

Q3 A6: Whether in God there are any accidents?

No. God can have no incidental characteristics (a.k.a. "accidents") because of His essential simplicity.

Accidents play a role in actualizing the potentiality of an underlying subject. But God is Pure Act with no admixture of potentiality.

Because God is His own existence, He does not need anything added incidentally to His essence.

In things, essential characteristics are caused by constituent principles. But God is First Cause, meaning there is nothing caused in Him. So He does not have essential characteristics the way that things do. He simply is.

Q3 A5: Whether God is contained in a genus?

No. God is not classifiable as a species of any genus because God is Pure Act, whereas the actuality of a specific difference is required to differentiate the potentiality of a genus.

Neither is God the purported genus "being". True, His existence is His essence, but as Aristotle demonstrated in the Metaphysics, being cannot be a genus.

Because His essence does not differ from His existence, there can be no definition of God. As the principle of all being, He cannot be classified by any genus.

Q3 A4: Whether essence and existence are the same in God?

Yes. Essentially, God is His existence because His existence alone is uncaused.

God is already Pure Act, and so existence is not required to actuate His form or nature (because His essence is already identical with His existence).

God is essential, not participated, being. Essentially, He is His existence, and not merely his own essence. God's existence is His essence.

Q3 A3: Whether God is the same as His essence or nature?

Yes. God is His essence because His nature is to be.

In other words, His form is the same as His suppositum, whereas this is not the case in material beings (which are composed by matter and form).

Q3 A2: Whether God is composed of matter and form?

No. God is not composed of matter and form. There is no matter in God because matter is potentiality, whereas God is Pure Actuality (as we demonstrated in Q2 A3).

Form perfects matter, because matter participates the form. But God is the essential good prior to any participated good.

Every agent acts by its form. God is First Agent because He is of His essence a form.

Thus God cannot be a composite being composed of the correlative principles of matter and form.

Q3 A1: Whether God is a body?

No. God is not a body because He is the Unmoved First Mover who is Pure Act and therefore Most Noble (i.e., more noble in being than mobile beings).

The essence of God

Having considered the existence of God, we now proceed to the questions (QQ.3-13) that treat of his essence.

We cannot know what God is, but only what He is not. So to study Him, we study what He has not -- such as composition and motion. His simplicity (3) or lack of composition. His perfection: and because everything in so far as it is perfect is called good, we shall speak of His goodness (6) -- and goodness in general (5) -- as well as His perfection (4). His infinity (7) and omnipresence (8). His immutability (9), and His eternity (10) following on His immutability. His unity (11). How God is known by us (12). The names of God (13).

Q2 A3: Whether God exists?

Yes. God exists because this is demonstrable from his actual effects.

There are five ways for making an a posteriori demonstration of his existence, but the first way is most manifest.

Most people have difficulty grasping these demonstrations. William A. Wallace, however, explains them well. But it takes much effort and rigorous intellectual training to grasp them fully.

Q2 A2: Whether it can be demonstrated that God exists?

Yes. The existence of God is demonstrable because we can reason from effect to cause.

This is called an a posteriori demonstration.

The science of nature makes use of this sort of reasoning all the time.

Q2 A1: Whether the existence of God is self-evident?

No. The existence of God is not self-evident because the essence of God is not self-evident to us (although it is so in itself, e.g., to God).

The existence of God

Having discussed sacred doctrine in the first question of the Prima Pars, we now move on to discuss the existence of God in question two, which is divided into three articles:

1. Is the proposition "God exists" self-evident?
2. Is it demonstrable?
3. Does God exist?

Q1 A10: Whether in Holy Scripture a word may have several senses?

Yes. Scripture has many senses because it signifies meaning not only by words but also by things themselves (which also have signification).

SIGNIFICATIONS (and hence senses of scripture):
1. historical or literal
2. spiritual:
(i) allegorical
(ii) moral
(iii) anagogical

Note the Reply to Objection 2: The literal sense includes:
(i) history (anything in a simple relation)
(ii) etiology (a cause is assigned to a thing)
(iii) analogy (affirming the noncontradiction of Scripture)

Note the Reply to Objection 3: The literal sense also includes the parabolical, "that which is figured"; for example, "God's arm" signifies, not an arm, but his operative power.

Q1 A9: Whether Holy Scripture should use metaphors?

Yes. Sacred doctrine rightly employs metaphors and similes because all our knowledge originates from the senses.

Thus we may ascend to spiritual truth from material things.

Q1 A8: Whether sacred doctrine is a matter for argument?

Yes, but sacred doctrine is argument from its principles, not for them, because sacred doctrine either answers rational objections to faith, or it reasons from articles of faith to answer objections to other articles of faith.

Arguments against faith are not demonstratively certain, but rather merely answerable difficulties, since faith rests on infallible truth.

Q1 A7: Whether God is the object of this science?

Yes. God is the object of sacred doctrine because all that sacred doctrine treats refers from effects to God as beginning and end.

That's why it's called theo-logy (science of God).

Q1 A6: Whether sacred doctrine is the same as wisdom?

Yes. Sacred doctrine is especially called wisdom because it is greater than human wisdom.

Sacred doctrine essentially treats of God as the highest cause, not just a posteriori (reasoning from effect to cause) as in natural theology, but rather as He is known to Himself alone and has revealed to others.

Q1 A5: Whether sacred doctrine is nobler than other sciences?

Yes. Sacred doctrine is nobler than other sciences because its certitude is greater (since human reason can err, but divine knowledge cannot) and because its subject matter is worth more (since its subject matter is the things which transcend reason's grasp).

For example, in the ranking of greater goods, eternal bliss is nobler than political science, just as political science is nobler than military science, because what is more noble is ordained to a purpose higher than that which is less noble. The purpose of the state is greater than the army; yet eternal bliss is far greater than both.