6. THE STATIC AND THE CHANGING.—The things we see around us, the things
which make up the immediate data of our experience, not only _are_ or
_exist_; they also _become_, or _come_ into actual existence; they
_change_; they pass out of actual existence. The abstract notion of being
represents its object to the mind in a static, permanent, changeless,
self-identical condition; but if this condition were an adequate
representation of reality change would be unreal, would be only an
illusion. This is what the Eleatic philosophers of ancient Greece
believed, distinguishing merely between being and nothingness. But they
were mistaken; for change in things is too obviously real to be eliminated
by calling it an illusion: even if it were an illusion, this illusion at
least would have to be accounted for. In order, therefore, to understand
reality we must employ not merely the notion of being (something
_static_), but also the notion of becoming, change, process, appearing and
disappearing (something _kinetic_, and something _dynamic_). In doing so,
however, we must not fall into the error of the opposite extreme from the
Eleatics—by regarding change as the adequate representation of reality.
This is what Heraclitus and the later Ionians did: holding that nothing
_is_, that all _becomes_ (πάντα ρέι), that change is all reality, that the
stable, the permanent, is non-existent, unreal, an illusion. This too is
false; for change would be unintelligible without at least an abiding
_law_ of change, a permanent _principle_ of some sort; which, in turn,
involves the reality of some sort of abiding, stable, permanent being.
We must then—with Aristotle, as against both of those one-sided
conceptions—hold to the reality both of being and of becoming; and proceed
to see how the stable and the changing can both be real.
To convince ourselves that they are both real, very little reflection is
needed. We have actual experience of both those elements of reality in our
consciousness and memory of our own selves. Every human individual in the
enjoyment of his mental faculties knows himself as an abiding,
self-identical being, yet as constantly undergoing real changes; so that
throughout his life he is really the same being, though just as certainly
he really changes. In external nature, too, we observe on the one hand
innumerable processes of growth and decay, of motion and interaction; and
on the other hand a similarly all-pervading element of sameness or
identity amid all this never-ending change.
7. THE POTENTIAL AND THE ACTUAL. (_a_) POSSIBILITY, ABSOLUTE, RELATIVE,
AND ADEQUATE.—It is from our experience of actuality and change that we
derive not only our notion of temporal duration, but also our notion of
_potential being_ or _possibility_, as distinct from that of _actual
being_ or _actuality_. It is from our experience of what actually exists
that we are able to determine what can, and what cannot exist. We know
from experience what gold is, and what a tower is; and that it is
intrinsically possible for a golden tower to exist, that such an object of
thought involves no contradiction, that therefore its existence is not
impossible, even though it may never actually exist as a fact. Similarly,
we know from experience what a square is, and what a circle is; and that
it is intrinsically impossible for a square circle to exist, that such an
object of thought involves a contradiction, that therefore not only is
such an object never actually existent in fact, but that it is in no sense
real, in no way possible.
Thus, _intrinsic_ (or _objective_, _absolute_, _logical_, _metaphysical_)
possibility is the mere non-repugnance of an object of thought to actual
existence. Any being or object of thought that is conceivable in this way,
that can be conceived as capable of actually existing, is called
intrinsically (or objectively, absolutely, logically, metaphysically)
possible being. The absence of such intrinsic capability of actual
existence gives us the notion of the intrinsically (objectively,
absolutely, logically, metaphysically) impossible. We shall return to
these notions again. They are necessary here for the understanding of real
change in the actual universe.
Fixing our attention now upon the real changes which characterize the data
of our experience, let us inquire what conditions are necessary in order
that an intrinsically possible object of thought become here and now an
actual being. It matters not whether we select an example from the domain
of organic nature, of inorganic nature, or of art—whether it be an oak, or
an iceberg, or a statue. In order that there be here and now an actual
oak-tree, it is necessary not only (1) that such an object be
intrinsically possible, but (2) that there have been planted here an
actual acorn, _i.e._ an actual being having in it subjectively and really
the passive potentiality of developing into an actual oak-tree, and (3)
that there be in the actual things around the acorn active powers or
forces capable of so influencing the latent, passive potentiality of the
acorn as gradually to evolve the oak-tree therefrom. So, too, for the (1)
intrinsically possible iceberg, there are needed (2) water capable of
becoming ice, and (3) natural powers or forces capable of forming it into
ice and setting this adrift in the ocean. And for the (1) intrinsically
possible statue there are needed (2) the block of marble or other material
capable of becoming a statue, and (3) the sculptor having the power to
mould this material into an actual statue.
In order, therefore, that a thing which is not now actual, but only
intrinsically or absolutely possible, become actual, there must actually
exist some being or beings endowed with the _active power or potency_ of
making this possible thing actual. The latter is then said to be
_relatively, extrinsically_ possible—in relation to such being or beings.
And obviously a thing may be possible relatively to the power of one
being, and not possible relatively to lesser power of another being: the
statue that is intrinsically possible in the block of marble, may be
extrinsically possible relatively to the skilled sculptor, but not
relatively to the unskilled person who is not a sculptor.
Furthermore, relatively to the same agent or agents, the production of a
given effect, the doing of a given thing, is said to be _physically_
possible if it can be brought about by such agents acting according to the
ordinary course of nature; if, in other words they have the physical power
to do it. Otherwise it is said to be physically impossible, even though
metaphysically or intrinsically possible, _e.g._ it is physically
impossible for a dead person to come to life again. A thing is said to be
_morally_ possible, in reference to free and responsible agents, if they
can do it without unreasonable inconvenience; otherwise it is considered
as morally impossible, even though it be both physically and
metaphysically possible: as often happens in regard to the fulfilment of
one’s obligations.
That which is _both intrinsically and extrinsically possible_ is said to
be _adequately possible_. Whatever is intrinsically possible is also
extrinsically possible in relation to God, who is _Almighty_,
_Omnipotent_.
8. (_b_) SUBJECTIVE “POTENTIA,” ACTIVE AND PASSIVE.—Furthermore, we
conceive the Infinite Being, Almighty God, as capable of _creating_, or
producing actual being _from nothingness_, _i.e._ without any actually
pre-existing material out of whose passive potentiality the actual being
would be developed. Creative power or activity does not need any
pre-existing subject on which to exercise its influence, any subject in
whose _passive potentiality_ the thing to be created is antecedently
implicit.
But all other power, all activity of created causes, does require some
such actually existing subject. If we examine the activities of the
agencies that fall within our direct experience, whether in external
nature or in our own selves, we shall find that in no case does their
operative influence or causality extend beyond the production of changes
in existing being, or attain to the production of new actual being out of
nothingness. The forces of nature cannot produce an oak without an acorn,
or an iceberg without water; nor can the sculptor produce a statue except
from some pre-existing material.
The _natural_ passive potentiality of things is, moreover, limited
in reference to the active powers of the created universe. These,
for example, can educe life from the passive potentiality of
inorganic matter, but only by assimilating this matter into a
living organism: they cannot restore life to a human corpse; yet
the latter has in it the capacity to be restored to life by the
direct influence of the Author of Nature. This special and
supernatural potentiality in created things, under the influence
of Omnipotence, is known as _potentia obedientalis_.(72)
This consideration will help us to realize that all reality which is
produced by change, and subject to change, is essentially a mixture of
_becoming_ and _being_, of _potential_ and _actual_. The reality of such
being is not _tota simul_. Only immutable being, whose duration is
_eternal_, has its reality _tota simul_: it alone is _purely actual_, the
“_Actus Purus_”; and its duration is one eternal “_now_,” without
beginning, end, or succession. But mutable being, whose duration in actual
existence is measured by _time_, is actualized only successively: its
actuality at any particular instant does not embody the whole of its
reality: this latter includes also a “_was_” and “_will be_”; the thing
was _potentially_ what it now is _actually_, and it will become actually
something which it now is only potentially; nor shall we have understood
even moderately the nature or essence of any mutable being—an oak-tree,
for example—until we have grasped the fact that the whole reality of its
nature embraces more than what we find of it actually existing at any
given instant of its existence. In other words, we have to bear in mind
that the reality of such a being is not pure actuality but a mixture of
potential and actual: that it is an _actus non-purus_, or an _actus
mixtus_.
We have to note well that the _potential being_ of a thing is something
_real_—that it is not merely a _modus loquendi_, or a _modus
intelligendi_. The oak is in the acorn in some true and real sense: the
potentiality of the oak is something real in the acorn: if it were not so,
if it were nothing real in the acorn, we could say with equal truth that a
man or a horse or a house is potentially in the acorn; or, again with
equal truth, that the oak is potentially in a mustard-seed, or a grain of
corn, or a pebble, or a drop of water. Therefore the oak is _really_ in
the acorn—not actually but potentially, _potentia passiva_.
The oak-tree is also really in those _active_ forces of nature whose
influence on the acorn develop the latter into an actual oak-tree: it is
in those causes not actually, of course, but _virtually_, for they possess
in themselves the _operative power_—_potentia activa sive operativa_—to
educe the oak-tree out of the acorn. These two potential conditions of a
being—in the active causes which produce it, and in the pre-existing
actual thing or things from which it is produced—are called each a real or
subjective potency, _potentia realis_, or _potentia subjectiva_, in
distinction from the mere logical or objective possibility of such a
being.
And just as the passive potentiality of the statue is something real in
the block of marble, though distinct from the actuality of the statue and
from the process by which this is actualized, so is the active power of
making the statue something real in the sculptor, though distinct from the
operation by which he makes the statue. If an agent’s _power_ to act, to
produce change, were not a reality in the agent, a reality distinct from
the _action_ of the latter; or if a being’s capacity to undergo change,
and thereby to become something other, were not a reality distinct from
the process of change, and from the actual result of this process—it would
follow not only that the actual alone is real, and the merely possible or
potential unreal, but also that no change can be real, that nothing can
really become, and nothing really disappear.(73)
9. (_c_) ACTUALITY: ITS RELATION TO POTENTIALITY.—It is from our
experience of change in the world that we derive our notions of the
potential and the actual, of active power and passive potentiality. The
term “act” has primarily the same meaning as “action,” “operation,” that
process by which a change is wrought. But the Latin word _actus_ (Gr.
ἐνέργεια, ἐντελέχεια) means rather that which is achieved by the _actio_,
that which is the correlative and complement of the passive potentiality,
the actuality of this latter: that by which potential being is rendered
formally actual, and, by way of consequence, this actual being itself.
“_Potentia activa_” and its correlative “_actus_” might, perhaps, be
appropriately rendered by “_power_” (_potestas agendi_) and “_action_” or
“_operation_”; “_potentia passiva_” and its correlative “_actus_,” by
“_potentiality_” and “_actuality_” respectively.
In these correlatives, the notion underlying the term “actual” is
manifestly the notion of something completed, achieved, perfected—as
compared with that of something incomplete, imperfect, determinable, which
is the notion of the potential. Hence the notions of _potentia_ and
_actus_ have been extended widely beyond their primary signification of
power to act and the exercise of this power. Such pairs of correlatives as
the determinable and the determined, the perfectible and the perfected,
the undeveloped or less developed and the more developed, the generic and
the specific, are all conceived under the aspect of this widest relation
of the potential to the actual. And since we can distinguish successive
stages in any process of development, or an order of logical sequence
among the contents of our concept of any concrete reality, it follows that
what will be conceived as an _actus_ in one relation will be conceived as
a _potentia_ in another. Thus, the disposition of any faculty—as, for
example, the scientific habit in the intellect—is an _actus_ or perfection
of the faculty regarded as a _potentia_; but it is itself a _potentia_
which is actualized in the _operation_ of actually studying. This
illustrates the distinction commonly drawn between an “_actus primus_” and
an “_actus secundus_” in any particular order or line of reality: the
_actus primus_ is that which presupposes no prior actuality in the same
order; the _actus secundus_ is that which does presuppose another. The act
of knowing is an _actus secundus_ which presupposes the cognitive faculty
as an _actus primus_: the faculty being the _first_ or fundamental
equipment of the soul in relation to knowledge. Hence the child is said to
have knowledge “_in actu primo_” as having the faculty of reason; and the
student to have knowledge “_in actu secundo_” as exercising this faculty.
The _actus_ or perfecting principles of which we have spoken so far are
all conceived as presupposing an existing subject on which they supervene.
They are therefore _accidents_ as distinct from _substantial constitutive_
principles of this subject; and they are therefore called _accidental_
actualities, _actus_ “_accidentales_”. But the actual existence of a being
is also conceived as the complement and correlative of its essence: as
that which makes the latter actual, thus transferring it from the state of
mere possibility. Hence existence also is called an _actus_ or actuality:
the _actus_ “_existentialis_,” to distinguish it from the existing thing’s
activities and other subsequently acquired characters. In reference to
these existence is a “first actuality”—“_Esse est actus primus_”; “_Prius
est esse quam agere_”: “Existence is the first actuality”; “Action
presupposes existence”—while each of these in reference to existence, is a
“second actuality,” an _actus secundus_.
When, furthermore, we proceed to examine the constitutive principles
essential to any being in the concrete, we may be able to distinguish
between principles which are determinable, passive and persistent
throughout all essential change of that being, and others which are
determining, specifying, differentiating principles. In water, for
example, we may distinguish the passive underlying principle which
persists throughout the decomposition of water into oxygen and hydrogen,
from the active specifying principle which gives that substratum its
specific nature as water. The former or material principle (ὕλη,
_materia_) is _potential_, compared with the latter or formal principle
(μορφή, εἶδος, ἐντελέχεια, _forma_, _species_, _actus_) as _actual_. The
concept of _actus_ is thus applied to the essence itself: the _actus_
“_essentialis_” or “_formalis_” of a thing is that which we conceive to be
the ultimate, completing and determining principle of the essence or
nature of that thing. In reference to this as well as the other
constitutive principles of the thing, the actual existence of the thing is
a “second actuality,” an _actus secundus_.
In fact all the constitutive principles of the essence of any existing
thing, and all the properties and attributes involved in the essence or
necessarily connected with the essence, must all alike be conceived as
logically antecedent to the existential _actus_ whereby they are
constituted something in the actual order, and not mere possible objects
of our thought. And from this point of view the existence of a thing is
called the ultimate actualization of its essence. Hence the scholastic
aphorism: “_Esse est ultimus actus rei_”.
The term _actus_ may designate that complement of reality by which
potential being is made actual (_actus_ “_actuans_”), or this actual being
itself (_actus_ “_simpliciter dictus_”). In the latter sense we have
already distinguished the Being that is immutable, the Being of God, as
the _Actus Purus_, from the being of all mutable things, which latter
being is necessarily a mixture of potential and actual, an _actus mixtus_.
Now if the essences of corporeal things are composite, if they are
constituted by the union of some determining, formative principle with a
determinable, passive principle—of “form” with “matter,” in scholastic
terminology—we may call these formative principles _actus_
“_informantes_”; and if these cannot actually exist except in union with a
material principle they may be called actus “_non-subsistentes_”: _e.g._,
the formative principle or “_forma substantialis_” of water, or the vital
principle of a plant. If, on the other hand, there exist essences which,
being simple, do not actualize any material, determinable principle, but
subsist independently of any such, they are called _actus_
“_non-informantes_,” or _actus_ “_subsistentes_”. Such, for example, are
God, and pure spirits whose existence is known from revelation. Finally,
there may be a kind of actual essence which, though it naturally
actualizes a material principle _de facto_, can nevertheless continue to
subsist without this latter: such an actual being would be at once an
_actus informans_ and an _actus subsistens_; and such, in fact, is the
human soul.
Throughout all distinctions between the potential and the actual there
runs the conception of _the actual as something more perfect than the
potential_. There is in the actual something positive and real over and
above what is in the potential. This is an ultimate fact in our analysis;
and its importance will be realized when we come to apply the notions we
have been explaining to the study of change.
The notion of grades of perfection in things is one with which everyone is
familiar. We naturally conceive some beings as higher upon the scale of
reality than others; as having “more” reality, so to speak—not
necessarily, of course, in the literal sense of size or quantity—than
others; as being more perfect, nobler, of greater worth, value, dignity,
excellence, than others. Thus we regard the infinite as more perfect than
the finite, spiritual beings as nobler than material beings, man as a
higher order of being than the brute beast, this again as surpassing the
whole vegetable kingdom, the lowest form of life as higher on the scale of
being than inorganic matter, the substance-mode of being as superior to
all accident-modes, the actualized state of a being as more perfect than
its potential state, _i.e._ as existing in its material, efficient and
ideal or exemplar causes. The grounds and significance of this mental
appreciation of relative values in things must be discussed elsewhere. We
refer to it here in order to point out another scholastic aphorism,
according to which the higher a thing is in the scale of actual being, and
the more perfect it is accordingly, the more efficient it will also be as
a principle of action, the more powerful as a cause in the production of
changes in other things, the more operative in actualizing their passive
potentialities; and conversely, the less actual a thing is, and therefore
the more imperfect, the greater its passive capacity will be to undergo
the influence of agencies that are actual and operative around it. “As
passive potentiality,” says St. Thomas,(74) “is the mark of potential
being, so active power is the mark of actual being. For a thing acts, in
so far as it is actual; but is acted on, so far as it is potential.” Our
knowledge of the nature of things is in fact exclusively based on our
knowledge of their activities: we have no other key to the knowledge of
what a thing is than our knowledge of what it does: “_Operari sequitur
esse_”: “_Qualis est operatio talis est natura_”—“Acting follows being”:
“Conduct is the key to nature”.
A being that is active or operative in the production of a change is said
to be the efficient cause of the change, the latter being termed the
effect. Now the greater the change, _i.e._ the higher and more perfect be
the grade of reality that is actualized in the change, the higher too in
the scale of being must be the efficient cause of that change. There must
be a proportion in degree of perfection or reality between effect and
cause. The former cannot exceed in actual perfection the active power, and
therefore the actual being, of the latter. This is so because we conceive
the effect as being produced or actualized _through the operative
influence_ of the cause, and _with real dependence_ on this latter; and it
is inconceivable that a cause should have power to actualize other being,
distinct from itself, which would be of a higher grade of excellence than
itself. The nature of efficient causality, of the influence by which the
cause is related to its effect, is not easy to determine; it will be
discussed at a subsequent stage of our investigations (ch. xi.); but
whatever it be, a little reflection should convince us of the truth of the
principle just stated: that an effect cannot be more perfect than its
cause. The mediæval scholastics embodied this truth in the formula: _Nemo
dat quod non habet_—a formula which we must not interpret in the more
restricted and literal sense of the words _giving_ and _having_, lest we
be met with the obvious objection that it is by no means necessary for a
boy to have a black eye himself in order to give one to his neighbour!
What the formula means is that an agent cannot give to, or produce in, any
potential subject, receptive of its causal influence, an actuality which
it does not itself possess virtually, or in its active power: that no
actuality surpassing in excellence the actual perfection of the cause
itself can be found thus virtually in the active power of the latter.
There is no question of the cause or agent transferring bodily as it were
a part of its own actuality to the subject which is undergoing change(75);
nor will such crude imagination images help us to understand what real
change, under the influence of efficient causality, involves.(76) An
analysis of change will enable us to appreciate more fully the real
difficulty of explaining it, and the futility of any attempt to account
for it without admitting the real, objective validity of the notions of
actual and potential being, of active powers or forces and passive
potentialities in the things that are subject to change.
10. ANALYSIS OF CHANGE.—_Change_ (_Mutatio_, _Motus_, μεταβολή, κίνησις)
is one of those simplest concepts which cannot be defined. We may describe
it, however, as _the transition of a being from one state to another_. If
one thing entirely disappeared and another were substituted for it, we
should not regard the former as having been changed into the latter. When
one thing is put in the place of another, each, no doubt, undergoes a
change of place, but neither is changed into the other. So, also, if we
were to conceive a thing as absolutely ceasing to exist, as lapsing into
nothingness at a given instant, and another as coming into existence out
of nothingness at the same instant (and in the same place), we should not
consider this double event as constituting a real change of the former
thing into the latter. And although our _senses_ cannot testify to
anything beyond _sequence_ in sense phenomena, our _reason_ detects in
real change something other than a total substitution of things for one
another, or continuous total cessations and inceptions of existence in
things. No doubt, if we conceive the whole phenomenal or perceptible
universe and all the beings which constitute this universe as essentially
contingent, and therefore dependent for their reality and their actual
existence on a Supreme, Necessary Being who created and conserves them,
who at any time may cease to conserve any of them, and produce other and
new beings _out of nothingness_, then such absolute cessations and
inceptions of existence in the world would not be impossible. God might
_annihilate_, _i.e._ cease to conserve in existence, this or that
contingent being at any instant, and at any instant _create_ a new
contingent being, _i.e._ produce it in its totality from no pre-existing
material. But there is no reason to suppose that this is what is
constantly taking place in Nature: that all change is simply a series of
annihilations and creations. On the contrary, the modes of being which
appear and disappear in real change, in the transition of anything from
one state to a really different state of being, do not appear _de novo_,
_ex nihilo_, as absolute beginnings out of nothingness; or disappear
_totaliter_, _in nihilum_, as absolute endings or lapses of reality into
nothingness. The real changes which take place in Nature are due to the
operation of natural causes. These causes, being finite in their operative
powers, cannot create, _i.e._ produce new being from nothingness. They
can, however, with the concurrence of the Omnipotent Being, modify
existing modes of being, _i.e._ make actual what was only potential in
these latter. The notion of change is not verified in the conception of
successive annihilations and creations; for there is involved in the
former concept not merely the notion of a real difference between the two
_actual_ states, that before and that after the change, but also the
notion of some _potential_ reality persisting throughout the change,
something capable of being actually so and so before the change and
actually otherwise after the change. For real change, therefore, we
require (1) two positive and really different states of the same being, a
“_terminus a quo_” and a “_terminus ad quem_”; and (2) a real process of
transition whereby something potential becomes actual. In creation there
is no real and positive _terminus a quo_; in annihilation there is no real
and positive _terminus ad quem_; these therefore are not changes in the
proper sense of the term. Sometimes, too, change is affirmed, by purely
extrinsic denomination, of a thing in which there is no real change, but
only a relation to some other really changing thing. In this sense when an
object unknown or unthought of becomes the actual object of somebody’s
thought or cognition, it is said to “change,” though the transition from
“unknown” to “known” involves no real change of state in the object, but
only in the knowing subject. If thought were in any true sense
“constitutive” of reality, as many modern philosophers contend, the change
in the object would of course be real.
Since, therefore, change consists in this, that a thing which is actually
in a given state ceases to be actually such and begins to be actually in
another state, it is obvious that there persists throughout the process
some reality which is in itself potential and indifferent to either actual
state; and that, moreover, something which was actual disappears, while
some new actuality appears, in this persisting potentiality. The abiding
potential principle is called the _matter_ or _subject_ of the change; the
transient actualizing principles are called _forms_. Not all these “forms”
which precede or result from change are necessarily positive entities in
themselves: they may be mere _privations_ of other forms (“_privatio_,”
στέρησις): not all changes result in the acquisition of a new degree of
positive actual being; some result in loss of perfection or actuality.
Still, even in these cases, the state characterized by the less perfect
degree of actuality has a determinate actual grade of being which is
proper to itself, and which, as such, is not found actually, but only
potentially, in the state characterized by the more perfect degree of
actuality. When, then, a being changes from a more perfect to a less
perfect state, the actuality of this less perfect state cannot be
adequately accounted for by seeking it in the antecedent and more perfect
state: it is not in this latter state _actually_, but only _potentially_;
nor do we account for it by saying that it is “equivalently” in the
greater actuality of the latter state: the two actualizing principles are
really distinct, and neither is wholly or even partially the other. The
significance of this consideration will appear presently in connection
with the scholastic axiom: _Quidquid movetur ab alio movetur_.
Meanwhile we must guard against conceiving the potential or material
factor in change as a sort of actual but hidden core of reality which
itself persists unchanged throughout; and the formative or actualizing
factors as superficially adorning this substratum by constantly replacing
one another. Such a substitution of imagination images for intellectual
thought will not help, but rather hinder, all accurate analysis. It is not
the potential or material factor in things that changes, nor yet the
actualizing or formal factors, but the things themselves; and if “things”
are subject to “real change” it is manifest that this fact can be made
intelligible, if at all, only by intellectually analysing the things and
their changes into constitutive principles or factors which are nor
themselves “things” or “changes”. Were we to arrive only at principles of
the latter sort, so far from explaining anything we would really only have
pushed back the problem a step farther. It may be that none of the
attempts yet made by philosophers or scientists to offer an ultimate
explanation of change is entirely satisfactory,—the scholastic explanation
will be gradually outlined in these pages,—but it will be of advantage at
least to recognize the shortcomings of theories that are certainly
inadequate.
We are now in a position to state and explain the important scholastic
aphorism embodying what has been called the Principle of Change
(“_Principium Motus_”): _Quidquid movetur, ab alio movetur_: “Whatever
undergoes change is changed by something else”. The term _motus_ is here
taken in the wide sense of any real transition from potentiality to
actuality, as is evident from the alternative statements of the same
principle: _Nihil potest seipsum reducere e potentia in actum_: “Nothing
can reduce itself from potentiality to actuality,” or, again, _Potentia,
qua talis, nequit per semetipsam ad actum reduci, sed reducitur ab alio
principio in actu_: “The potential as such cannot be reduced by itself to
the actual, but only by some other already actual principle”.(77) This
assertion, rightly understood, is self-evidently true; for the state of
passive potentiality, as such, involves the absence of the correlative
actuality in the potential subject; and since the actual, as such,
involves a perfection which is not in the potential, the latter cannot
confer upon itself this perfection: nothing can be the adequate principle
or source of a perfection which is not in this principle or source: _nemo
dat quod non habet_.
We have already anticipated the objection arising from the consideration
that the state resulting from a change is sometimes in its totality less
perfect than the state which existed prior to the change. Even in such
cases there results from the change a new actuality which was not in the
prior state, and which cannot be conceived as a mere part or residue of
the latter, or regarded as equivalently contained in the latter. Even
granting, as we must, that the net result of such a change is a loss of
actuality or perfection in the subject of change, still there is always a
gain which is not accounted for by the loss; there is always a new actual
state which, as such, was not in the original state.
A more obvious objection to the principle arises from the consideration of
vital action; but it is based on a misunderstanding of the principle under
discussion. Living things, it is objected, move themselves: their _vital_
action is spontaneous and immanent: originating within themselves, it has
its term too within themselves, resulting in their gradual development,
growth, increase of actuality and perfection. Therefore it would appear
that they move and perfect themselves; and hence the so-called “principle
of change” is not true universally.
In reply to all this we admit that vital action is immanent, remaining
within the agent to perfect the latter; also that it is spontaneous,
inasmuch as when the agent is actually exercising vital functions it need
not be actually undergoing the causal influence of any other created
agent, or actually dependent on any such agent. But it must, nevertheless,
in such action, be dependent on, and influenced by, _some actual being
other than itself_. And the reason is obvious: If by such action it
increases its own actual perfection, and becomes actually other than it
was before such action, then it cannot have given itself the actuality of
this perfection, which it possessed before only potentially. No doubt, it
is not merely passively potential in regard to such actual perfections, as
is the case in non-vital change which results in the subject from the
transitive action of some outside cause upon the latter. The living thing
has the active power of causing or producing in itself these actual
perfections: there is interaction between its vital parts: through one
organ or faculty it acts upon another, thus educing an actuality, a new
perfection, in this other, and thus developing and perfecting its own
being. But even considered as active it cannot be the adequate cause of
the actuality acquired through the change. If this actuality is something
_really_ over and above the reality of its active and passive potential
principles, then it remains true that change implies the influence of an
actual being other than the subject changed: _Quid quid movetur, ab alio
movetur_.
The question here arises, not only in reference to vital agents,
but to _all finite, created causes_: Does the active cause of
change (together with the passive potentiality of the subject of
change, whether this subject be the agent itself as in immanent
activity, or something other than the agent as in transitive
activity),—does this active power account _adequately_ for the new
actuality educed in the change? It obviously does not; for the
actuality acquired in the change is, as such, a new entity, a new
perfection, in some degree positively surpassing the total reality
of the combined active powers and passive potentialities which it
replaces. In other words, if the actuality resulting from the
change is not to be found in the immediate active and passive
antecedents of the change, then we are inevitably referred, for an
adequate explanation of this actuality, to some actual being above
and beyond these antecedents. And to what sort of actual being are
we referred? To a being in which the actuality of the effect
resides only in the same way as it resides in the immediate active
and passive antecedents of the change, that is _potentially_? No;
for this would be useless, merely pushing the difficulty one step
farther back. We are obliged rather to infer the existence of an
Actual Being in whom the actuality of the said effect resides
_actually_: not formally, of course, as it exists in itself when
it is produced through the change; but eminently, _eminenter_, in
such a way that its actualization outside Himself and under His
influence does not involve in Him any loss of perfection, any
increase of perfection, or any manner of change whatsoever. We are
compelled in this way to infer, from the existence of change in
the universe of our direct experience, the existence of a
transcendent Immovable Prime Mover, a _Primum Movens Immobile_.
All the active causes or principles of change which fall under our
notice in the universe of direct experience are themselves subject
to change. None of them causes change in any other thing without
itself undergoing change. The active power of finite causes is
itself finite. By educing the potentiality of other things into
actuality they gradually use up their own energy; they diminish
and lose their active power of producing effects: this belongs to
the very nature of finite causes as such. Moreover, they are
themselves passive as well as active; interaction is universal
among the finite causes which constitute the universe of our
direct experience: they all alike have passive potentiality and
undergo change. Now, if any one finite cause in this system cannot
adequately account for the new actuality evolved from the
potential in any single process of change, neither can the whole
system adequately account for it. What is true of them
distributively is true of them taken all together when there is
question of what belongs to their nature; and the fact that their
active powers and passive potentialities _fall short_ of the
actuality of the effects we attribute to them is a fact that
appertains to their very nature as finite things. The phenomenon
of continuous change in the universe involves the continuous
appearance of _new actual being_. To account for this constant
stream of actuality we are of necessity carried beyond the system
of finite, changing being itself; we are forced to infer the
existence of a source and principle which must itself be purely
actual and exempt from all change—a Being who can cause all the
actuality that results from change without losing or gaining or
changing in any way Himself, because He possesses all finite
actuality in Himself in a supereminent manner which transcends all
the efforts of finite human intelligence to comprehend or
characterize in any adequate or positive manner. The scholastics
expressed this in the simple aphorism: _Omne novum ens est a Deo_.
And it is the realization of this profound truth that underlies
their teaching on the necessity of the Divine _Concursus_, _i.e._
the influence of the Infinite First Cause or Prime Mover
permeating the efficiency of all finite or created causes. Here,
for example, is a brief recent statement of that doctrine:—
“If we must admit a causal influence of these things [of direct
experience] on one another, then a closer examination will
convince us that a finite thing can never be the adequate cause of
any effect, but is always, metaphysically regarded, only a
part-cause, ever needing to be completed by another cause. Every
effect is—at least under one aspect, at least as an
effect—something new, something that was not there before. Even
were the effect contained, whether formally or virtually, in the
cause, it is certainly not identical with this latter, for if it
were there would be no causality, nothing would ‘happen’. In all
causing and happening, something which was heretofore only
possible, becomes real and actual. But things cannot determine
themselves to influence others, or to receive the influence of
others, since they are not dependent in their being on one
another. Hence the necessary inference that all being, all
happening, all change, requires the concurrence of an Absolute
Principle of being. When two things act on each other the Absolute
Being must work in and with them, the same Absolute Being in
both—to relate them to each other, and supplement their natural
insufficiency.”
“Such is the profound teaching about the Divine Concursus with
every creature.... God works in all and with all. He permeates all
reality, everywhere; there is no being beyond Him or independent
of His conserving and concurring power. Just as creatures are
brought into being only through God’s omnipotence, and of
themselves have no independent reality, so do they need the
self-same ever-present, all-sustaining power to continue in this
being and develop it by their activity. Every event in Nature is a
transitory, passing phenomenon, so bound up with conditions and
circumstances that it must disappear to give place to some other.
How could a mode of being so incomplete discharge its function in
existence without the concurrence of the First Cause?”(78)
We have seen now that _in the real order_ the potential presupposes the
actual; for the potential cannot actualize itself, but can be actualized
only by the action of some already actual being. Nor can we avoid this
consequence by supposing the potential being to have had no actual
beginning in time, but to be eternally in process of actualization; for
even so, it must be eternally actualized _by some other actual being_—a
position which Aristotle and some scholastics admit to be possible.
Whether, then, we conceive the actualization as beginning in time or as
proceeding from all eternity, it is self-contradictory to suppose the
potential as capable of actualizing itself.
It is likewise true that the actual precedes the possible _in the order of
our knowledge_. The concept of a thing as possible presupposes the concept
of that thing as actual; for the possible is understood to be possible
only by its intelligible relation to actual existence. This is evidently
true of extrinsic possibility; but our knowledge even of the intrinsic
possibility of a thing cannot be the first knowledge we possess in the
order of time. Our first knowledge is of the actual; for the mind’s first
cognitive act must have for object either itself or something not itself.
But it knows itself as a consciously acting and therefore actual being.
And it comes to know things other than itself only by the fact that such
other things act upon it either immediately or mediately through
sense-consciousness; so that in every hypothesis its first known object is
something actual.(79)
The priority of the actual as compared with the potential in the
real order, suggests a proof of the existence of God in the manner
indicated above. It also affords a refutation of Hegelian monism.
The conception of the world, including all the phenomena of mind
and matter, as the gradual self-manifestation or evolution of a
potential being eternally actualizing itself, is a
self-contradictory conception. Scholastics rightly maintain that
the realities from which we derive our first most abstract and
transcendental notion of being in general, are actual realities.
Hegelians seize on the object of this notion, identify it with
pure thought, proclaim it the sole reality, and endow it with the
power of becoming actually everything. It is manifest, therefore,
that they endow purely potential being with the power of
actualizing itself.
Nor can they fairly avoid this charge by pointing out that
although their starting-point is not actual being (with which the
scholastic philosophy of being commences), yet neither is it
possible or potential being, but being which has neither of these
determinations, being which abstracts from both, like the real
being of the scholastics (7, 13). For though real being can be _an
object of abstract human thought_ without either of the predicates
“existent” or “non-existent,” yet it cannot be anything _in the
real order_ without either of them. There it must be either
actually existent or else merely potential. But Hegelians claim
absolutely indeterminate being to be _as such_ something in the
real order; and though they try to distinguish it from potential
being they nevertheless think of it as potential being, for they
distinctly and repeatedly declare that it can become all things,
and does become all things, and is constantly, eternally
transforming itself by an internal dialectic process into the
phenomena which constitute the worlds of mind and matter.
Contrasting it with the abstract “inert” being which they conceive
to be the object of the traditional metaphysics, they endow
“indeterminate being” with the active power of producing, and the
passive potentiality of becoming, actually everything. Thus, in
order to show _a priori_ how this indeterminate being must evolve
itself by internal logical necessity into the world of our direct
and immediate experience, they suppose it to be subject to change
and to be at the same time self-actualizing, in direct opposition
to the axiom that potential reality, reality which is subject to
change, cannot actualize itself: _Quidquid movetur ab alio
moveatur oportet_.
11. KINDS OF CHANGE.—Following Aristotle,(80) we may recognize a broad and
clear distinction between four great classes of change (μεταβολή,
_mutatio_) in the phenomena of our sense experience: local change (κίνησις
κατὰ τόπον, φορά, _latio_); quantitative change (κατὰ τὸ πόσον, ἀύζησις ἤ
φθίσις, _augmentatio vel diminutio_); qualitative change (κατὰ τὸ ποίον,
ἀλλοίωσις, _alteratio_); and substantial change (κατ᾽ οὐσίαν, γένεσις ἤ
φθορά). The three former are accidental, _i.e._ do not reach or affect the
essence or substance of the thing that is changed; the fourth is
substantial, a change of essence. Substantial change is regarded as taking
place instantaneously, as soon as the condition brought about by the
accidental changes leading up to it becomes naturally incompatible with
the essence or nature of the subject. The accidental changes, on the other
hand, are regarded as taking place gradually, as realizing and involving a
succession of states or conditions in the subject. These changes,
especially when they take place in corporeal things, are properly
described as movement or motion (_motus_, _motio_). By movement or motion
in the strict sense we therefore mean any change which takes place
gradually or successively in a corporeal thing. It is only in a wider and
improper sense that these terms are sometimes applied to activity of
whatsoever kind, even of spiritual beings. In this sense we speak of
thoughts, volitions, etc., as movements of the soul, _motus animae_; or of
God as the Prime Mover ever in motion, the _Primum Movens semper in motu_.
With local change in material things, as also with quantitative change,
growth and diminution of quantity (mass and volume), everyone is perfectly
familiar. From the earliest times, moreover, we find both in science and
philosophy the conception of matter as composed of, and divisible into,
ultimate particles, themselves supposed to admit of no further real
division, and hence called _atoms_ (ἄ-τομος, τέμνω). From the days of
Grecian atomism men have attempted to show that all change in the Universe
is ultimately reducible to changes of place, order, spatial arrangement
and collocation, of those hypothetical atomic factors. It has likewise
been commonly assumed that change in mass is solely due to change in the
number of those atoms, and change in volume (of the same mass) to the
relative density or closeness with which the atoms aggregate together;
though some have held—and it is certainly not inconceivable—that exactly
the same material entity, an atom let us say, may be capable of _real_
contraction and expansion, and so of _real_ change of volume: as distinct
from the _apparent_ contraction and expansion of bodies, a change which is
supposed to be due to change of density, _i.e._ to decrease or increase in
the dimensions of the pores or interstices between the smaller constituent
parts or molecules. However this may be, the attempts to reduce all change
in physical nature to mere _mechanical_ change _i.e._ to spatial motions
of the masses (_molar_ motions), the molecules (_molecular_ motions), and
the atoms or other ultimate components of matter (whether vibratory,
undulatory, rotatory or translational motions), have never been
satisfactory.
Qualitative change is wider than material change, for it includes changes
in spiritual beings, _i.e._ in beings which are outside the category of
quantity and have a mode of existence altogether different from the
extensional, spatial existence which characterizes matter. When, for
instance, the human mind acquires knowledge, it undergoes qualitative
change. But matter, too, has qualities, and is subject to qualitative
change. It is endowed with _active_ qualities, _i.e._ with powers, forces,
energies, whereby it can not merely perform mechanical work by producing
local changes in the distribution of its mass throughout space, but also
produce physical and chemical changes which seem at least to be different
in their nature from mere mechanical changes. It is likewise endowed with
_passive_ qualities which appear to the senses to be of various kinds,
differing from one another and from the mechanical or quantitative
characteristics of size, shape, motion, rest, etc. While these latter are
called “primary qualities” of bodies—because conceived to be more
fundamental and more closely inherent in the real and objective nature of
matter—or “common sensibles” (_sensibilia communia_), because perceptible
by more than one of our external senses—the former are called “secondary
qualities,” because conceived to be less characteristic of the real and
objective nature of matter, and more largely subjective products of our
own sentient cognitive activity—or “proper sensibles” (_sensibilia
propria_), because each of them is apprehended by only one of our external
senses: colour, sound, taste, odour, temperature, material state or
texture (_e.g._ roughness, liquidity, softness, etc.). Now about all these
perceived qualities and their changes the question has been raised: Are
they, as such, _i.e._ as perceived by us, really in the material things or
bodies which make up the physical universe, and really different in these
bodies from the quantitative factors and motions of the latter? Or, as
such, are they not rather partially or wholly subjective
phenomena—products, at least in part, of our own sense perception, states
of our own consciousness, having nothing really corresponding to them in
the external matter of the universe beyond the quantitative, mechanical
factors and motions whereby matter acts upon our faculties of sense
cognition and produces these states of consciousness in us? This is a
question of the first importance, the solution of which belongs to
Epistemology. Aristotle would not allow that the objective material
universe can be denuded, in the way just suggested, of qualities and
qualitative change; and scholastic philosophers have always held the same
general view. What we have to note here, however, in regard to the
question is simply this, that even if the world of matter were thus
simplified by transferring all qualitative change to the subjective domain
of consciousness, the reality of qualitative change and all the problems
arising from it would still persist. To transfer qualitative change from
object to subject, from matter to mind, is certainly something very
different from explaining it as reducible to quantitative or mechanical
change. The simplification thus effected would be more apparent than real:
it would be simplifying the world of matter by transferring its complexity
to the world of mind. This consideration is one which is sometimes lost
sight of by scientists who advance mechanical hypotheses as ultimate
explanations of the nature and activities of the physical universe.
If all material things and processes could be ultimately analysed into
configurations and local motions of space-occupying atoms, homogeneous in
nature and differing only in size and shape, then each of these ultimate
atomic factors would be itself exempt from intrinsic change as to its own
essence and individuality. In this hypothesis there would be really no
such thing as _substantial_ change. The collection of atoms would form an
immutable core of material reality, wholly simple and ever actual. Such an
hypothesis, however, is utterly inadequate as an explanation of the facts
of life and consciousness. And even as an account of the processes of the
inorganic universe it encounters insuperable difficulties. The common
belief of men has always been that even in this domain of reality there
are fundamentally different _kinds_ of matter, kinds which differ from one
another not merely in the shape and size and configuration and arrangement
of their ultimate _actual_ constituents, but even in the very substance or
nature of these constituents; and that there are some material changes
which affect the actual substance itself of the matter which undergoes
them. This belief scholastics, again following Aristotle, hold to be a
correct belief, and one which is well grounded in reason. And this belief
in turn involves the view that every type of actual material
entity—whether merely inorganic, or endowed with life, or even allied with
a higher, spiritual mode of being as in the case of man himself—is
_essentially composite_, essentially a synthesis of _potential_ and
_actual_ principles of being, and therefore capable of _substantial_
change. The actually existing material being scholastics describe as
_materia secunda_, the ὕλη ἐσχάτη of Aristotle; the purely potential
factor, which is actualized in this or that particular kind of matter,
they describe as _materia prima_, the ὕλη πρώτη of Aristotle; the
actualizing, specifying, formative principle, they designate as _forma
substantialis_ (εἶδος). And since the purely potential principle cannot
actually exist except as actualized by some formative principle, all
substantial change or transition from one substantial type to another is
necessarily both a _corruptio_ and a _generatio_. That is, it involves the
actual disappearance of one substantial form and the actual appearance of
another. Hence the scholastic aphorism regarding substantial change:
_Corruptio unius est generatio alterius_: the corruption or destruction of
one kind of material thing involves the generation of another kind.
The concepts of _materia prima_ and _forma substantialis_ are concepts not
of phenomenal entities directly accessible to the senses or the
imagination, but of principles which can be reached only mediately and by
intellect proper. They cannot be pictured in the imagination, which can
only attain to the sensible. We may help ourselves to grasp them
intellectually by the analogy of the shapeless block of marble and the
figure educed therefrom by the sculptor, but this is only an analogy: just
as the statue results from the union of an _accidental_ form with an
existing matter, so this matter itself, the substance _marble_, is
composed of a _substantial_ form and a primordial, _potential_ matter. But
there the analogy ceases.
Furthermore, when we consider that the proper and primary objects of the
human intellect itself are corporeal things or bodies, and that these
bodies actually exist in nature only as composite substances, subject to
essential or substantial change, we shall realize why it is that the
concept of _materia prima_ especially, being a mediate and negative
concept, is so difficult to grasp; for, as the scholastics describe it,
translating Aristotle’s formula, it is in itself _neque quid, neque
quantum, neque quale, neque aliquid eorum quibus ens determinatur_.(81)
But it is through intellectual concepts alone, and not through imagination
images, that we may hope to analyse the nature and processes even of the
world of corporeal reality; and, as St. Thomas well observes, it was
because the ancient Greek atomists did not rise above the level of
thinking in imagination images that they failed to recognize the
existence, or explain the nature, of substantial change in the material
universe(82): an observation which applies with equal force to those
scientists and philosophers of our own time who would fain reduce all
physical processes to mere mechanical change.
Those, then, are the principal kinds of change, as analysed by Aristotle
and the scholastics. We may note, finally, that the distinction between
_immanent_ and _transitive_ activity is also applied to change—that is, to
change considered as a process, not to the result of the change, to change
_in fieri_, not _in facto esse_. Immanent movement or activity (_motio_,
_actio immanens_) is that of which the term, the educed actuality, remains
within the agent—which latter is therefore at once both _agens_ and
_patiens_. Vital action is of this kind. Transitive movement or activity,
on the other hand (_motio_, _actio transiens_), is that of which the term
is some actuality educed in a being other than the agent. The _patiens_ is
here really distinct from the _agens_; and it is in the former, not in the
latter, that the change takes place: _actio fit in passo_. All change in
the inorganic universe is of this sort (101).