[This topic is treated in Modes of the Finite, Part 2, Section 3.]
10.1. Changes vs. replacement
Most sciences focus primarily on changes, not because scientists are in love with "innovation," but because change is the most obvious case of an effect: something that doesn't make sense by itself, needing a cause to make sense out of it.
In fact, let me now reveal a secret I have been keeping for several chapters: our own investigation into the finiteness of the appearance was actually an examination of the fact that our act of consciousness changes; and this means that one and the same consciousness becomes different from itself while still being the same as itself. And this, in fact, is the really the definition of change, so let's make it formal:
• DEFINITION: A change occurs when one and the same thing becomes different from itself.
That is, there is some sense in which you can say after the change, "This is not what it used to be," but since you are using "this," the word implies "This is what it used to be." The body after the change is both the same and different.
Obviously, if there is no noticeable difference after a lapse of time, then we say that no change has taken place; so there has to be a difference of some sort. But if there is no sameness between the "before" and "after," we would not say that the object changed, but that it had been replaced. That is, when the magician puts the handkerchief into the hat and pulls out a rabbit, then he would like you to believe that the handkerchief changed into the rabbit (because there was no rabbit in the hat beforehand, and there is no handkerchief there now). But any intelligent person knows that handkerchiefs can't and therefore don't change into rabbits, and so somehow without our noticing it, he moved the handkerchief out of the hat and put a rabbit (which had been existing as a rabbit all along) into it. So mere substitution doesn't constitute a change, since there is nothing by which we can say that the "after" is one and the same thing as the "before."
10.1.1. Change and the spiritual
It seems obvious to us that everything changes. But even though this might be true of everything we experience, it turns out that not everything can change.
For instance, the Infinite can't change, since He is just plain old pure activity. In order to change, He would have to be different afterwards, which would mean that He would be finite (and no longer be Infinite)--which, incidentally, would mean that absolutely everything (including this new "finite-Infinite") would suddenly not exist, since nothing finite can exist without having its existence caused by infinite existence. And so "changing" would not be changing at all, but self-annihilation, (along with the annihilation of absolutely everything else). But there's nothing in the Infinite to prompt such a move (how could He "want" it, since in what sense would He be "better off" if He did it?); and so we can rule that out. Anyhow, there's no sense in which He now lacks what He will become, since the activity which He is is just pure, unlimited, unqualified and unquantified existence. So He can't change at all, in any way.
It turns out that pure spiritual acts can't change either, for an analogous reason. Since any pure spirit is a single act and not a system (since every "part" of a spirit would be contained within every other "part," and even the whole as a whole would be "contained" in each "part," since the act itself "does itself" as many times as you want to name without actually being more than one single act--this is the characteristic of not having quantity, where numbers are meaningless), then it follows that there aren't two distinguishable "aspects" in a pure spirit by which it could be said to be "the same in this respect" and "different in this other respect."
So if Gabriel were to be "transformed" into Raphael (to take names for two different kinds of pure spirit) then something about Gabriel would have to continue throughout the change, or we'd have simple substitution of one for the other. That is, if you annihilated Gabriel and created Raphael from nothing, then in what sense is it true that Raphael used to be Gabriel? No sense at all. So no change took place. You can't even say that the new Raphael "took the place" of Gabriel, since "place" only exists among those being which have fields to interact with each other, and these fields are forms of energy with quantities--and so only bodies exist in a place.
Nor can a pure spirit "change an idea" or behavior of any sort. You would suspect this because bodies have many behaviors because they are multiple units, and a spiritual act, while it might be called "multiple" in some sense (since it is the act of knowing X and "also" the act of knowing-you-know X) has no real multiplicity in it. But the real point is that any "unit" in the spiritual "multiplicity" contains all the other ones as well as the whole itself (since all there really is is one single act), then any difference in any aspect is in fact a difference in the whole act (since that's all there really is).
Hence, no change at all is possible in a pure spirit.(1) How boring! you say. Not at all. You get bored and want to do something different, because at any given moment, you're not doing all that you can be doing. But if you suppose that you were forever and ever doing absolutely every act you were capable of doing (as would be the case with a pure spirit, who exhausts the whole form of activity), then you wouldn't and couldn't be bored doing this forever. What more could you want?
10.2. Conditions for change
In any case, if pure spirits can't change, then you need energy to be able to change. We will shortly see why. but for now, we can at least draw the following conclusion:
TWENTY-FIFTH CONCLUSION: Only bodies can change.
There has to be something in the body by which it can be said to be "the same" throughout the change, and something else by which it can be said to be "different." Aristotle thought that in what we will shortly call "accidental" changes, the "substance" (the body) remained the same and the "accident" was replaced, while in what is called "substantial" change, the "stuff" the thing was made of (the matter) remained the same and the "substantial form" (the form of the unifying energy) got replaced. This was also basically the view of St. Thomas Aquinas--not surprisingly, since St. Thomas was a follower of Aristotle.
But I think it's a good deal more complicated than that. First of all, the notion that in an accidental change the body remains the same implies that the body is a kind of "pincushion" that you can stick "accidents" into or remove from without its affecting the body in any real way. But the "accident," the behavior is the existence of the body, one of its modes of finiteness. If it "has" a "new" accident, this is not something that "happens" to it, it means that the body as a whole is doing something new--which implies that the body as a whole is somehow different from what it was. So a "replacement" of the "accident" has got to imply a difference in the "substance" somehow, which leaves the problem back where it was. Similarly, once you say (as St. Thomas did) that the "stuff" is really the limitation of the "substantial form," then in a substantial change, how can the limitation remain the same if it's just the nothingness of the act and the act is different?
Now this is not to say that Thomists don't have answers to this; the subject of change, by which something is and is not itself, is going to be quite mysterious any way you look at it (as is any other instance of the finite); and there are ways of understanding what I just sketched that make sense and are at least on the right track.
But I think modern science has opened the door to a different way of looking at the subject, and so I offer my own theory, based on it.
• BASIC HYPOTHESIS: A given form of unifying energy can only exist at a certain energy-level (i.e. with a certain definite quantity).
So a certain type of body also implies a certain total energy in the body, because the unifying energy has to hold the body together, and it is capable of uniting this amount of energy, and no more and no less. That's the hypothesis.(2)
This allows us to talk about two different conditions a body can be in:
• DEFINITION: A body is in equilibrium when the form of the unifying energy is limited to the "proper" degree.
That is, in this case, the body has the "right" level of unifying energy, and hence the "right" total amount of energy in the parts.
• The characteristic of equilibrium is that if nothing interferes with the body, it will continue as it is indefinitely.
This is true because there is nothing in it that would make it "need" to be different, and by the supposition (that nothing is interfering with it), nothing from outside is disturbing the equilibrium. And so it will just continue doing the same thing forever and ever.
• DEFINITION: A body is unstable if the form of the unifying energy is limited to the "wrong" degree.
• The characteristic of instability is that it is impossible for a body to exist as unstable.
Obviously, if the body is unstable (if the unifying energy has a quantity it can't exist with, which means that the total energy in the parts is greater or less than what the unifying energy can unify), then it's got to get rid of the instability somehow.
What I'm calling "instability" Aristotle called being "in potency," meaning being in the condition of being "deprived" of a form the body doesn't at the moment have. Obviously, if the body is "deprived" of something, it needs it, and so it changes to get it. I think that what I have done is spelled out what the being looks like when it is "in potency" to be something else.
Before we get into what happens, let me point out that there's a difference in equilibrium between inanimate and living bodies. In inanimate bodies, the only equilibrium the body has is called the "ground state," the condition in which the form of the unifying energy has the greatest limitation (or in other words in which it is the least amount of energy for this particular type of unifying energy)--which in turn implies that the total energy of the body is the smallest amount of energy that is capable of being unified in this way. Hence, inanimate instability is always an excess of energy. The inanimate body, when it's unstable, always has too much energy, and has to get rid of it or restructure itself to handle it.
But living bodies, which as bodies have this ground-state equilibrium, have an additional, higher-energy state peculiar to each body as living: the biological equilibrium. Thus, a living body can be unstable either because it has too much total energy (implying that the unifying energy is too energetic to exist at this degree--just like an inanimate body), or too little (implying that the unifying energy is too weak).
It might be interesting to pursue this difference here, but it is not really proper to the science of metaphysics, but belongs in the Philosophy of Nature and the Philosophy of Living Bodies, so I am going to leave it with just this mention.
10.3. Types of changes
In discussing the historical theories of change I mentioned "accidental change" and "substantial change." Even though I am no fan of "substance" and "accident" as a theory of bodies and their behaviors, I see no special reason for not using the traditional terms dealing with change, since they aren't misleading.
So let us say that some energy has acted on a body, giving it more energy than it can handle, making the unifying energy unstable. What can happen? One of two things:
• DEFINITION: An accidental change is a change in which the body gets rid of the excess energy (or acquires the proper amount of needed energy) and so returns to equilibrium.
That is, the body does something (performs some behavior) which either gives off the excess energy (as when a billiard ball moves when struck), or acquires the needed energy (as when you breathe or eat); and the end result is that it is back where it started.
• The characteristic of accidental change is that the body remains the same kind of body. The energy-level of the body is different during the change (e.g. while the body is moving), because it's trying to lose the excess energy it has. But once the change is over and the ball has rubbed off the excess energy by friction on the pool table, then it comes to rest (in a new place, of course), and is the same as if nothing ever happened to it. The point is that the form of the unifying energy is what remains "constant" in this change, while the degree of this form gets replaced. Of course, this "degree" is simply the limitation of the form of existence, and is a difference in the form itself; and so it's still very mysterious.
The other thing that can happen, of course, is this:
• DEFINITION: A substantial change is a change in which the unifying energy "restructures itself" with a new form of activity, making the body a new kind of body.
In this case, the body can't get rid of the excess energy by performing a new act. But it can't exist as it is. Hence, it ceases to exist as it is, and some form of activity that can handle this new energy-level takes its place. For instance, if you hit the billiard ball hard enough, you might impart so much energy to it that you wouldn't just move it, you would break it. In that case, the body can't deal with the excess energy by moving, and it simply becomes two different bodies (and you will find that the total energy of the "parts"--i.e. what used to be parts but now are separate bodies--is greater than the equilibrium energy of the whole).
• It turns out from observation to be a law that in a change, the total quantity of the activities involved remains constant.
This is the so-called "law of the conservation of energy" or sometimes "conservation of matter," or "conservation of mass-energy." They are all different ways of saying the same thing: the total amount of energy in any interaction involving a change remains constant (of course, to discover this, you have to use the relevant "conversion factors" to map one form of energy onto another).
This sort of thing is what you would expect from the definition above. The form of the unifying energy is replaced, but the quantity carries through the change, and lets us say that this new kind of thing once was such-and-such. Thus, when you burn wood, the ashes used to be wood, and the quantity of the products of combustion is exactly equal to the total energy when the fire started. (The ashes in this case are lighter, but the ashes plus the gases and the heat given off are also products of combustion.) Also, in the case of accidental change, since it gets rid of the excess energy introduced, then obviously the amount of energy in the unstable body and the amount of energy in the newly stable body plus the energy given off are going to turn out to be the same.
So the theory seems to hold together. There are points about it which create difficulties, but absent something better, this will have to do.
10.4. Efficient cause
I said earlier that a body in equilibrium will remain that way forever unless interfered with. But then how does a body get out of equilibrium? Obviously, it can't do it by itself. This is especially evident in inanimate bodies, since their equilibrium is their lowest energy-level. In order for the body to get itself out of equilibrium, it would have to give itself more total energy than it has, which is absurd. Living bodies are a special case, however, which I will mention briefly below.
But let us take it that equilibrium is the natural condition of a body, and instability is unnatural. The unnatural obviously has to be forced from outside upon what is natural. And this is why scientists like changes so much; the unstable body automatically "speaks about" some other body that got it into this unnatural condition.
• DEFINITION: An efficient cause is something outside a body which accounts for the instability of a body.
Generally speaking, this efficient cause will be some form of energy: the energy absorbed by the body that makes it unstable. The efficient causer, of course, is the other body which gave up the energy. Thus, when the earth gets warm on the bright side, the efficient cause is the heat radiating out from the sun; and of course the sun is the efficient causer.
But of course, the efficient cause can be any activity that can make a body unstable, conceivably even a spiritual activity (which of course is infinitely greater than any form of energy, because, even if it is a form of activity and not the Infinite, it is precisely above the limitation implied in quantity). Thus, the efficient cause of the words I see appearing on the screen is really my (spiritual) choice to write those words. My choice rearranges the energy in my brain, which makes my muscles unstable, which makes my fingers tap the right keys (most of the time), which makes the words appear on the screen. Similarly, the Infinite as accounting for the finiteness of any finite act can be called the efficient cause of the act. (In this case, the cause and the causer are in reality one and the same, since the Infinite is nothing but the Infinite Act).
So it is not necessarily just changes that have efficient causes, if you use the term in its analogous sense. It would be any effect in any being which can only be made sense of by something outside the being. Note that by Theorem I of Chapter 3 the cause (any cause) is always outside the effect but it may or may not be outside the being in which the effect is the abstract conflict between two facts (i.e. the affected object). When the cause is outside the affected object, it's called an efficient cause.
As to changes in living bodies, let me say this: They have, as I said, a high-energy biological equilibrium in addition to the ground-state equilibrium. This means (1) that they have a more or less considerable amount of "reserve energy" that they're not using for behaviors at the moment, but which they can use at any moment (since the body doesn't need this much energy just to exist; it's above its ground state). Further, (2) they can rearrange this excess energy within themselves, using some of it from one part as a kind of "efficient cause" to create an instability in another part.
Hence, a living body can make itself unstable in certain ways without being acted on by an efficient cause. So a dog can fall asleep and then just spontaneously wake up without actually being roused by any noise or other disturbance. When the sleep activity has done its work within the body, then the unifying energy turns off the sleep mechanism and turns on the waking mechanism, and the body as a whole wakes up.
In this way, a living body can "move itself," as Aristotle says, without being moved by something else. This is especially true of human beings, who have a spiritual "component" to their unifying energy, and can make conscious choices. These choices are spiritual acts, and they can spontaneously rearrange the energy in the brain; and so the "efficient cause" is the choice of the person himself. We will see a bit more of this in passing in the next section. I do not want to discuss it fully, because this is metaphysics, not the philosophy of living beings.
We come now to another one of Aristotle's "four causes" that I mentioned in Chapter 3: the "final cause."
If you look a bit more closely at instability, it not only "talks about" what is behind itself (the efficient cause), it also refers to what is ahead of itself and doesn't exist yet. The unstable body can't exist as it is, and so it has to be in a different condition.
But the body's instability points it to a definite different condition, not just "something-or-other different," for the same reason that you can't jump on a horse and ride off in all directions. For the unstable body to just get out of the condition it's in into another condition that's just as unstable is absurd; and so it is headed toward equilibrium, and a definite equilibrium at that.
• DEFINITION: The purpose of a change is the equilibrium at the end of the change.
• Notice first of all that the purpose is not "to get to" the end; the purpose in the sense I'm using it is the goal or end of the change: the new equilibrium that removes the instability. "To get to" the end is "purpose" in the sense of "intention," and you can't say that a rock you drop "intends" in any real sense to be on the ground; it's just that it has too much energy, and the path by which it loses the energy most efficiently leads it down to the ground. It's just what's built into the structure of the body itself, not something it "wants." If anything, "to get to" the goal describes the direction of the change rather than the purpose in my sense of the term.
But as long as I've used the word, then let me relate "purpose" in my sense with "purpose" in the sense of the "intention" or "motive" for doing something--because it turns out that there is an analogy here.
What happens here is that we use our imaginations as we did when I described goodness in Chapter 6: we make up a state of affairs about ourselves that we would like to see exist, and set that up as ideal. But instead of sitting around and complaining ("evaluating" reality against the ideal), we then say to ourselves, "Well yes, but let's change things so that the reality becomes the ideal." The ideal then becomes a conceived goal.
The choice (a spiritual act) then takes that conceived goal and uses it to shift energy around in the brain, creating an instability in the body, which then has the purpose (in our sense of the term) of the equilibrium which corresponds to the conceived goal in the mind of the agent.
The point is that the difference between "purpose" in the sense of "motive" ("to get to" some goal) and purpose in my sense (which you can call "natural purpose") is not what happens once the instability is in the body, but how the instability got there.
That is, we choosers, who conceive our own purposes (animals have them built-in), study the way things are, and what instabilities we can put into various things (including our own bodies) and what purposes (natural purposes) these instabilities have. And then we set up an instability in ourselves which in turn sets up an instability in something else and that in something else and so on, until we have transformed the world.
So, for example, I realize that I need a desk for my computer. I imagine a table top big enough (a hundred feet long?), and legs and drawers and whatnot; and then I set up an instability in myself that goes and gets paper and pencils and rulers and sets up instabilities in them which results in plans on paper, and then set up further instabilities in myself (and my checkbook) whose purpose is to get a bunch of wood planks into my basement; and then I set up instabilities in these planks with saws and planes and whatnot whose purpose is the boards in the right sizes and then--well, you get the picture. Finally, the desk is sitting there, and I have achieved my "purpose" in the sense of my intention, and the changes in all that I've been acting on have reached their equilibrium and the whole process stops. I'm happy, and the world is once again at rest: that is, acting stably, and not heading itself toward a different condition.
Having got a clear idea of what is meant by "purpose," then, we can say the following:
TWENTY-SIXTH CONCLUSION: All changes have purpose.
This is obvious because nothing changes unless it is unstable, and instability of itself implies purpose. It is also true that
TWENTY-SEVENTH CONCLUSION: Equilibrium has no purpose; it makes sense by itself; it just is.
Something has a purpose only if it doesn't make sense in the condition it's in and has to be in a different condition. But equilibrium has no other problem except that of finite being, which does not in any sense imply that it "ought" to be different.
And so there's no reason for saying, "But everything has a purpose." Some things, as even Aristotle saw, are ends in themselves, and have no "purpose" except "to be what they are." But this is a "purpose" that's no purpose at all.(3)
Obviously, the Infinite can have no purpose in His activity, since it can't be different. Even supposing the choice to have that activity be the cause of finite existences is a free choice (though identical with His unchanging act) the "purpose" in creating can't be any gain for the Infinite, or any difference in the Infinite whatever. All it is as a "motive" is the realization that the act can cause this and that and the other finite being, and the acceptance of this. Then poof! the finite being.
So why does the finite being exist? Because the Infinite caused it. And why did the Infinite cause it? Because it can--in other words, why not. In that sense, the "purpose" of the Infinite in creating is the actual existence of the finite being, and not some goal it is "supposed" to reach because of the Infinite's "plan" for it.
But all of this needs further discussion--but not here. Read The Finite and the Infinite.
One more point, and then we're done with basic metaphysics. It's pretty obvious that few changes take place instantaneously, with the being in the unstable condition and then suddenly at the purpose. There's an act that is performed to get rid of the excess energy or to acquire the new energy (think how long it takes you to get that Big Mac into your system where it does you--good?).
Aristotle saw this act, using the example of construction to describe it. What is construction? It's not the act of the house, because when the bricks and so on are active as a house, they're in equilibrium (he didn't say it this way), and the construction has stopped. But it's not the act of the bricks as an incomplete house either, because you can stop the construction at this point, and the bricks go on existing as an incomplete house. He finally called the process, "The act of the potential (what is in my terminology 'unstable') as potential."
• DEFINITION: Process is the act by which the being removes its instability.
Another way of putting this is that the process is the act of getting to the purpose. In Aristotle's sense, it is the act of something that is unstable insofar as it is unstable--which is essentially what the definition above says, when you think about it. As unstable, it needs to be in equilibrium; process is what it is doing to get there.
So, for instance, the construction process is not the act of the bricks as bricks, nor the act of the bricks as a house, nor the act of the bricks as an incomplete house; it is the act of the bricks as headed toward acting as a house, or in other words, it's what the bricks are doing (actually, what's being done to them, but it's the same thing metaphysically) to get from being a pile of bricks to sticking together as a house.
Put it another way: process is the act of changing.
"Big deal!" you say. All right, you try to describe what it is.
• As Aristotle also pointed out (brilliant man, Aristotle), process is an incomplete activity. It is an activity that "points beyond" itself to the purpose, and it shows that the being that is acting this way is in a self-contradictory condition: it is not its real self yet.
This is true in more than a metaphorical sense. The unstable being is precisely self-contradictory as it exists; it can't exist in this way. And so, as soon as it "is" in an unstable condition, it stops being in that condition, and has taken an infinitesimal step in the direction of equilibrium. So its only meaningful reality is the purpose; as it now is, it stops existing in this way as soon as it exists in this way.
Georg Hegel said that reality is process; but in order to say this, he had to say that reality as such contradicts itself, and contains what is not itself (the goal, which doesn't exist) within itself. He alleged that this made sense, because in fact everything--he said--is in process (including what he called The Absolute, which is the Infinite plus the finite, which both need each other.)
He was mistaken. His philosophy is a good analysis of process and the finite generally; but you have to turn reason on its head to say that what contradicts itself is by definition what is "rational." What he didn't realize is that the contradiction in process and anything else that is finite implies equilibrium, not only as its goal, but as its efficient cause. His view that process is reality finitized the Infinite.
At any rate, if you have stuck with me this far, you have something of a notion of the basic structure of finite reality, and especially of those finite realities we call bodies.
SUMMARY OF CHAPTER 10
A change can't involve the object's remaining the same all the time, nor can it be a simple substitution of one thing for another, because in the latter case, there's no reason for saying that the first thing turned into the second. So a change occurs when one and the same thing becomes different from itself. After the change, it has to be both different from and the same as it was before.
The Infinite, then, cannot change, because if He were to become different, then He would be finite, and so nothing (including himself) could exist. Also, He can't lack whatever He would later have. Nor can a pure spirit change, because every aspect of a pure spirit "contains" all other aspects within it and is contained within each other aspect, since it is only one act, which (having no quantity) "does itself" many times without being many. If any aspect of it were to be different, then the whole would be a different being, and there would be nothing at all by which it could be said to be "the same as" it used to be. 25th conclusion: Only bodies can change.
The hypothesis for my theory of change is that a given form of unifying energy can only exist with a definite quantity; if it has any other quantity, it can't exist. The body is in equilibrium when its unifying energy has the quantity it "needs" (and therefore when the total energy of the body's parts is the "right amount" to be held together by this amount of unifying energy). Bodies in equilibrium will stay that way forever unless interfered with from outside. If the body gains energy, then the unifying energy is unstable, which means that it is limited by the "wrong" quantity: a quantity it can't exist with. An unstable body will immediately stop existing in this way (since it contradicts itself in this condition). In inanimate bodies, instability is always an excess of energy, since the equilibrium of an inanimate body is always the lowest energy-level it can exist at. Living bodies have in addition to this ground-state equilibrium a high-energy biological equilibrium, and so they can be unstable with too little as well as too much total energy.
If the body gets rid of the excess energy (or acquires the energy it needs), then this kind of change is called an accidental change, and the body remains the same kind of body (though the quantity of the unifying energy may differ, and so there is a difference in the unifying energy). If the body can't just readjust its energy-level, it restructures itself, and the unifying energy takes on a new form that can handle the new quantity it has. This is a substantial change, in which the body becomes a different kind of body. In changes, the total quantity of the activities involved remains constant.
If a body is in equilibrium, it will stay there. So if it is to become unstable, the instability is explained by an outside being (e.g. that adds energy to it). An efficient cause is something outside the body which accounts for the body's instability; the efficient causer is the outside body (or being, in general) that contains the efficient cause. Analogously, an efficient cause is an external act or which accounts for any effect within a being; thus the Infinite can be called an efficient cause of the finiteness of a finite being, even one in equilibrium. Living bodies, having biological equilibrium, have reserve energy that isn't used up in behavior, and which they can shift around from part to part, causing instabilities within the parts, which then result in new behavior that was caused from within. Thus, living bodies can change without having an efficient cause for the change.
Since an unstable body can't exist as unstable, but only in equilibrium, every instability is "headed toward" a definite equilibrium. The purpose of the change is the equilibrium the body is "headed towards": the equilibrium at the end of the change. "Purpose" in the sense of "intention" means that our choice spontaneously shifts energy around in our brain creating an instability in the body, whose purpose (in the true sense) is the end-state that was why the instability was created by the choice. So human purpose deals with how the instability got there; once it's there, the purpose is simply the end of the change. Note that purpose is not "to get to" the end; it's the end itself. 26th conclusion: All changes have purpose, because all changes involve instability, which implies a future equilibrium. 27th conclusion: Equilibrium has no purpose; it just is. Equilibrium makes sense by itself, and so needs no purpose. So only changes have purposes.
Not all bodies can get out of instability immediately into equilibrium. Process is the act by which a being gets itself from instability to its purpose; or in other words, process is the act of changing. Since process is the act of something insofar as it is unstable, it is necessarily an incomplete act, headed somewhere beyond itself; and it implies that the body that is in process is incomplete. Only equilibrium is complete activity.
1. A couple of remarks are in order here. This does not mean that the spirit can't be the causer of multiple effects on earth, say, as Gabriel caused effects on both Zechariah and Mary in announcing what was to happen to them. But causes are not altered by the fact that they have effects; and so Gabriel's unchanging act is such that at the proper time, it produces the effect on these people that he had, without his having to change. This would get more complicated to analyze thoroughly, but trust me, it is compatible with Gabriel's activity not actually changing in any way. Secondly, our spiritual acts change, because they are not purely spiritual. One of the "duplications" of the spiritual act of our consciousness is the electrical-energy-discharge of the nerves in the brain; and so one and the same act both has no quantity (in its spiritual "dimension") and is a form of energy (in its energy "dimension"). Because of the latter, that which is spiritual can change. But again, to prove this would take us very far afield indeed.
2. I have to qualify this by saying that in living bodies, there is not just one energy-level that is the "proper" one; they can (for reasons we won't have to go into here) exist at a number of different energy-levels, and so there can be many different instances of a given kind of thing, all existing in equilibrium. In the case of inanimate bodies, there is only one equilibrium energy-level for a given kind of body; that is, any instance of a hydrogen atom in equilibrium will have exactly as much total energy (and hence as much unifying energy) as any other one.
3. I should point out that there's a sense in which a living body in biological equilibrium has the purpose of staying that way, since the body as biologically stable is simultaneously (as a body) physically unstable and is therefore moving toward its ground state equilibrium. And so the body as living has to fight that tendency it has as a body, and bring itself back up to biological equilibrium by replacing the energy it is losing as (an unstable) body.