Papist Orthodoxy

October 13, 2009

The Metaphysical & Theological Implications in the Difference Between Ens Simpliciter & Ens Moblile

Filed under: Cosmology -- Philosophical Physics, Metaphysics, Philosophy — Tags: , , — Antiochian-Thomist @ 6:49 pm

Through the natural light of reason by which we come to know the causes of things and through divine revelation gratuitously given for the benefit of corrupted man we know that we composite creatures are not our own existence. However, man sees things even in the material order darkly and dimly, and his powers of perception beyond the material order are feeble at best. Further to work past the material order is a struggle most tedious and tiresome leaving many an individual holding such exercises as distasteful with the result that many resist such attempts to come to understand anything beyond the natural order of things. We are often like the poor souls in Plato’s cave analogy:

And if, said I, someone should drag him thence by force up the ascent which is rough and steep, and not let him go before he had drawn him out into the light of the sun, do you not think that he would find it painful to be so haled along, and would chafe at it..?1

But as distasteful as this exercise can be, it is worth it. What we can know is perhaps little, but what we can know is also certain when understood within their (and our) proper limitations. We exist -this we know. We need not undergo a Cartesian meditation to achieve certitude in this claim. We change -this we also know. Experience shows this to be the fact. But what implications are there in the consideration that existence is not the same as material being, or that there is existence apart from material being? What implications come with the consideration of motion/change? The consequences are literally beyond measure that forces an intellectual concession of a perennial truth accompanied by a moral consequence that necessarily follows upon such an intellectual concession. The fact that ‘to be’ (ens simpliciter) and ‘to be changeable’ (ens mobile) are not the same leads to the metaphysical and theological implication that there is an unchangeable being which we call God and that He is our last end for which we must act. Let us proceed, then, in this exercise by considering changeable being, motion, and then unchangeable being.

Changeable Being.

To maintain any solidity in the endeavor, let us proceed in ways more secure and assured for our purposes by considering first the things we know and then moving to the the things that we either know not, or know very little, or know with less certainty. For as is the common experience of a man when faced with a problem that he must solve and who will analyze the object as a general whole and work back through more particulars until he ultimately reaches that which he was investigating, so let us also proceed from those things more generally known to us to those things more known by nature. As Aristotle says:

The natural way of doing this is to start from the things which are more knowable and obvious to us and proceed towards those which are clearer and more knowable by nature; for the same things are not ‘knowable relatively to us’ and ‘knowable’ without qualification.2

Proceeding thusly we first come to know those things which present themselves to the five senses, for it is through the senses that the soul is informed. Those things that we perceive are first those things which are in some way whole and therefore general in a qualified sense, for it is not usually the case that we first experience the constituent parts of things before we come to know the whole, but that we first have a general perception of the whole and then work toward the constituent parts. In those instances where we encounter parts before the whole, we often walk confusedly until the general whole has been assembled in the mind before we rest in any certitude. Therefore, the wisdom of the Philosopher’s counsels are manifest:

Thus we must advance from generalities to particulars; for it is a whole that is best known to sense perception, and a generality is a kind of a whole, comprehending many things within it, like parts.3

But those general/whole things that we encounter are, quite frankly, things, which is to say that we encounter beings that exist, whether it be ‘man’, ‘dog’, ‘rock’, ‘cup’, etc. The first thing present to the mind via the senses is not so much the ‘thisness’ of the thing as it is the thing itself. Thus the first thing we know is not the existence of the thing but the existent thing. Therefore, we perceive a whole being without necessarily an initial and immediate consideration of the existence of the thing apart from the thing itself, for we could know it otherwise lest somehow we come first know things apart from senses. Furthermore, it can be added that what is first known is known without distinction between the material being and its act of existence. This, then, is our first understanding of being, viz. material being, which can only be known if its is real and is sensed. Thus the Common Doctor asserts that, “nothing can be called a being unless it is something positive in reality.”4

After the first experiences of material beings, we come to know them through the experiences of the senses as changeable or movable. We observe growth and diminution, coming to be and passing from existence, but we are still left with the concept of existence long after the material things’ existence has changed. For example, long after a subject has passed from being, as in death, we can still consider the subject and its act of existence, not only as the subject it was, but as the kind of subject it was, as when we consider Socrates, not as dead or as Socrates, but as man. Further, we notice not only substantial changes but accidental ones as well where the subject persists after the change. An example of this is the man who at one point is ignorant of geometry and later comes to know geometry. The man, as the subject, persists after the change from ignorance to knowledge, but his existence is now of a different quality, viz. that of the geometer. Another example of this is when we consider locomotion. A subject was once at A and is now at B; but after the subject is at B, its previous existence at A can still be considered and ruminated upon, not only as once being at A but as potentially being at A in the future. Finally, where it is that with sense perception also comes imagination whereby sensible things are brought to the intellect via phantasms, man has the ability to contrive things in the imagination that have no substantial existence in physical reality. Such is the case with Aristotle’s famous ‘goat-stag’ or the architect’s future cathedral. It is not real or not yet real; but its existence can be imagined. In these and in nigh-to-innumerable experiences like these, consideration of the experiences themselves and through themselves reveal that existence can be considered apart from material beings, that ‘to be’ is not the same as ‘to be changeable’.


To be a changeable being is to be a being in potency under a certain aspect. In short, it is to be a movable being. But what is motion? Aristotle defines motion as “the fulfillment of what exists potentially, insofar as it exists potentially.”5 St. Thomas states more simply that “motion is nothing else than the reduction of something from potentiality to actuality.”6 By these definitions, motion encompasses all change and is not merely reduced to locomotion. Therefore, insofar as a being has the potentiality of being something else (qualitatively, substantially, or otherwise), and insofar as that same being is in the process of becoming that something else, it is in motion. Examples of this are easy to come by. The block of marble being carved into a statue, the man walking across the room, the tree that starts as a sapling but is growing into a full oak -these are all examples of motion as each are in potency to what it is becoming and is in the process of being actualized. In short, they are being reduced from potentiality to actuality.

To consider change or motion, one must consider not just the act of motion, which is a coming to be, nor just the thing moved, but one must also consider the mover, for to be a material being, which is to say a changeable or movable being, is to be a moved being. It is therefore clear and manifest that there are things in the world that are moved, either by a mover or, apparently, by itself. However, Aristotle and St. Thomas both assert that whatever is moved is moved by another. Certainly this is clear in the cases of material beings which do not possess a principle of motion in themselves. However, what of those beings that do possess a principle of motion in themselves? Are they moved by another? In short: yes.

In his cogent and concise summation of Aristotle’s Physics, St. Thomas points out a pithy and packed reality pregnant with meaning and implication in his question on the existence of God. The Common Doctor says:

Now whatever is in motion is put in motion by another, for nothing can be in motion except it is in potentiality to that towards which it is in motion; whereas a thing moves inasmuch as it is in act. For motion is nothing else than the reduction of something from potentiality to actuality. But nothing can be reduced from potentiality to actuality, except by something in a state of actuality. Thus that which is actually hot, as fire, makes wood, which is potentially hot, to be actually hot, and thereby moves and changes it. Now it is not possible that the same thing should be at once in actuality and potentiality in the same respect, but only in different respects. For what is actually hot cannot simultaneously be potentially hot; but it is simultaneously potentially cold. It is therefore impossible that in the same respect and in the same way a thing should be both mover and moved, i.e. that it should move itself. Therefore, whatever is in motion must be put in motion by another. If that by which it is put in motion be itself put in motion, then this also must needs be put in motion by another, and that by another again.7

So as stated before, those things which have not a principle of motion in itself are obviously moved by another. But in the quotation above, St. Thomas includes all movables, both those which have a principle of motion in themselves and those which have not, as being subject to a mover apart from the moved. This is better understood when one considers that whatever is moved must itself be divisible.8 In short, those things that are called self-moving are not primarily self moving because they must move in virtue of their parts, for they cannot move through themselves simply. If these self movers could move themselves through themselves primarily, their motion would not be dependent upon the motion of another. But movables are divisible and the moved are so moved through their parts. So, in movable beings, if the part is moved, so is the whole. If the part is at rest, so is the whole. If a man moves by virtue of his feet and legs, the whole man is moving. If the man is to be truly at rest, all of his parts must truly be at rest. But his motion and rest depend on his parts. Thus he moves himself secondarily, as it were, and not through himself primarily. His motion, then, must primarily come from another. Therefore, whatever is moved is moved by another.9

This can be illustrated by an example most pertinent to our designs. Coming to be is a motion for artificial and natural material beings alike. In the case of an artifice such as a cathedral, its motion is received from the architect and the workers. Similarly, the coming into existence of a man and his sustainment therein is not a motion found in the man, for the man does not exist nor is he his own existence. The primary motion is therefore from another.

Though whatever is moved is moved by another, we cannot go on to infinity lest we have that infinite regress by which we would never have the moved. Thus St. Thomas says in the Summa Contra Gentiles:

If it is moved, it is moved by another mover. We must, consequently, either proceed to infinity, or we must arrive at some unmoved mover. Now, it is not possible to proceed to infinity. Hence, we must posit some prime unmoved mover.10

He further states in the Summa Theologica:

But this cannot go on to infinity, because then there would be no first mover, and, consequently, no other mover; seeing that subsequent movers move only inasmuch as they are put in motion by the first mover; as the staff moves only because it is put in motion by the hand. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God.11

With the understanding that whatever is moved is moved by another, we rapidly come to the unmoved mover, the cause of all motion.

The Unchangeable Being.

As stated earlier, Aristotle’s use of the term motion encompasses all change. But we have come to the unmoved mover. If the mover is Himself unmoved, we have then come to a being that does not admit of change. If He does not admit of change, then He does not admit of potentiality. A potentiality in material beings is that they potentially could ‘not be’ for they are not the same as their existence. As the unmoved mover does not admit of potentiality in any respect, non-existence is therefore impossible for Him. St. Thomas confirms this:

…The first being must of necessity be in act, and in no way in potentiality. For although in any single thing that passes from potentiality to actuality, the potentiality is prior in time to the actuality; nevertheless, absolutely speaking, actuality is prior to potentiality; for whatever is in potentiality can be reduced into actuality only by some being in actuality. Now it has been already proved that God is the First Being. It is therefore impossible that in God there should be any potentiality.12

However, it was also stated that ‘to be’ is not the same as ‘to be changeable’. For God, the unmoved mover, to be the first cause of motion, He must of necessity be. But in all other cases, coming to be as a motion must be caused by another. In God there is no motion which is to say, as above, He admits of no potentiality. Therefore, God does not differ from His existence. The Common Doctor demonstrates this well:

Existence is that which makes every form or nature actual; for goodness and humanity are spoken of as actual, only because they are spoken of as existing. Therefore existence must be compared to essence, if the latter is a distinct reality, as actuality to potentiality. Therefore, since in God there is no potentiality, as shown above (S.T. I, Q.3, a.1), it follows that in Him essence does not differ from existence. Therefore His essence is His existence.13

There are more necessary conclusions to be drawn about the existence of God, and those relate to the response of rational material creatures to this sublime reality of His existence. In other words, there are moral consequences that necessarily follow upon the recognition of the existence of God. For if God exists -and He does of necessity- and if God is the cause of all things -and He is- then it follows that God is the proper and final end of the entire material order, including that of man. For as all nature acts for an end14 so too does the rational nature of man15 and this he does by the operation of his will. Therefore, as all creatures have their existence by way of a participation, and as the highest object of the intellect of man is the unmoved mover, the first being, God, so too the highest object of the will of man and that for the sake of which man must act must be God. For, as St. Thomas asserts:

It is impossible for any created good to constitute man’s happiness. For happiness is the perfect good, which lulls the appetite altogether; else it would not be the last end, if something yet remained to be desired. Now the object of the will, i.e. of man’s appetite, is the universal good; just as the object of the intellect is the universal true. Hence it is evident that naught can lull man’s will, save the universal good. This is to be found, not in any creature, but in God alone; because every creature has goodness by participation. Wherefore God alone can satisfy the will of man, according to the words of Psalm 102:5: “Who satisfieth thy desire with good things.” Therefore God alone constitutes man’s happiness.16


This exercise provides just the briefest of sketches into the implications of existence as apart from material being from the philosophical perspective and serves as merely the rudimentary summation of a few concepts whose profundity has filled countless volumes of works by intellects of the highest of calibers. It is enough to show that differences between what it is ‘to be’ and ‘to be changeable’ have profound implications that can be knowable from the natural progression of philosophical reasoning which leaves man with little room for excuses. Further, considering the end for the sake of which these considerations show, it makes that steep climb out of Plato’s cave every bit worthwhile, for we can now see the prophetic truth in Plato’s words about the one who escapes the cave:

Well then, if he recalled to mind his first habitation and what passed for wisdom there, and his fellow bondsmen, do you not think that he would count himself happy in the change and pity them?17


Aquinas, St. Thomas. Commentary on Aristotle’s Physics. Notre Dame, Indiana: Dumb Ox Books, 1999.

_______. On Being and Essence. Toronto, Ontario, Canada: Pontifical Institute of Mediaeval Studies, 1968.

_______. Summa Contra Gentiles. Notre Dame, Indiana: University of Notre Dame Press, 1975.

_______. Summa Theologica (in English, 5 vols., Notre Dame, Indiana: Christian Classics,


Aristotle. Physics. (Richard McKeon, ed., The Basic Works of Aristotle, New York: Random

House, 1941.

Plato. Republic. (Edith Hamilton and Huntington Cairns, eds., The Collected Dialogues of Plato,

Princeton, New Jersey: Princeton University Press, 1989.

1Plato. Republic, VII, 515e.

2Aristotle. Physics, I, 184a15.

3Aristotle. Physics, I, 184a25.

4St. Thomas Aquinas. De Ente et Essentia, Chapter 1, paragraph 2.

5Aristotle. Physics, III, 1, 201 a10.

6St. Thomas Aquinas. Summa Theologica, I, Q.2, a.3.

7St. Thomas Aquinas. Summa Theologica, I, Q.2, a.3.

8Aristotle. Physics, VI, 4.

9St. Thomas Aquinas. Summa Contra Gentiles, Book I, Chapter 13.

10 ibid.

11 St. Thomas Aquinas. Summa Theologica, I, Q.2, a.3.

12 St. Thomas Aquinas, Summa Theologica, I, Q.3, a.1.

13 St. Thomas Aquinas. Summa Theologica, I, Q.3, a.4.

14 Aristotle. Physics, II, 5.

15 St. Thomas Aquinas. Summa Theologica, I-II, Q.1, a.2.

16 St. Thomas Aquinas. Summa Theologica, I-II, Q.1, a.8.

17 Plato. Republic, VII, 516 c.

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