ideal moment in substance. Aristotle begins (Phys. II. 8) with the
fact that the natural is the self-maintaining, all that is difficult
is its comprehension. “The first cause of perplexity is, what hinders
nature from not operating for the sake of an end, and because it is
better so to operate, but” being, for example, “like Jupiter, who
rains, not that the corn may grow, but from necessity. The vapour
driven upwards cools, and the water resulting from this cooling falls
as rain, and it happens that the corn is thereby made to grow. In like
manner, if the corn of any one is destroyed, it does not rain for the
sake of this destruction, but this is an accidental circumstance.”
That is to say, there is a necessary connection which, however, is an
external relation, and this is the contingency of the cause as well
as of the effect. “But if this be so,” Aristotle asks, “what hinders
us from assuming that what appears as parts” (the parts of an animal,
for instance) “may thus subsist in nature, too, as contingent? That,
for example, the front teeth are sharp and adapted for dividing,
and that the back teeth, on the contrary, are broad and adapted for
grinding the food in pieces, may be an accidental circumstance, not
necessarily brought about for these particular ends. And the same is
true with respect to the other parts of the body which appear to be
adapted for some end; therefore those living things in which all was
accidentally constituted as if for some end, are now, having once been
so existent, preserved, although originally they had arisen by chance,
in accordance with external necessity.” Aristotle adds that Empedocles
especially had these reflections, and represented the first beginnings
of things as a world composed of all sorts of monstrosities, such as
bulls with human heads; such, however, could not continue to subsist,
but disappeared because they were not originally constituted so that
they should endure; and this went on until what was in conformity with
purpose came together. Without going back to the fabulous monstrosities
of the ancients, we likewise know of a number of animal tribes which
have died out, just because they could not preserve the race. Thus
we also require to use the expression development (an unthinking
evolution), in our present-day natural philosophy. The conception that
the first productions were, so to speak, attempts, of which those which
did not show themselves to be suitable could not endure, is easily
arrived at by natural philosophy. But nature, as _entelecheia_ or
realization, is what brings forth itself. Aristotle hence replies: “It
is impossible to believe this. For what is produced in accordance with
nature is always, or at least for the most part, produced” (external
universality as the constant recurrence of what has passed away), “but
this is not so with what happens through fortune or through chance.
That in which there is an end (τέλος), equally in its character as
something which precedes and as something which follows, is made into
end; as therefore a thing is made, so is its nature, and as is its
nature, so is it made; it exists therefore for the sake of this.” The
meaning of nature is that as something is, it was in the beginning;
it means this inward universality and adaptation to end that realizes
itself; and thus cause and effect are identical, since all individual
parts are related to this unity of end. “He who assumes contingent and
accidental forms, subverts, on the other hand, both nature itself and
that which subsists from nature, for that subsists from nature which
has a principle within itself, by whose means, and being continually
moved, it attains its end.” In this expression of Aristotle’s we now
find the whole of the true profound Notion of life, which must be
considered as an end in itself—a self-identity that independently
impels itself on, and in its manifestation remains identical with
its Notion: thus it is the self-effectuating Idea. Leaves, blossoms,
roots thus bring the plant into evidence and go back into it; and that
which they bring to pass is already present in the seed from which
they took their origin. The chemical product, on the contrary, does
not appear to have itself similarly present, for from acid and base a
third appears to come forth; but here, likewise, the essence of both
these sides, their relationship, is already present, though it is
there mere potentiality, as it is in the product merely a thing. But
the self-maintaining activity of life really brings forth this unity
in all relationships. What has here been said is already contained in
that which was asserted by those who do not represent nature in this
way, but say, “that which is constituted as though it were constituted
for an end, will endure.” For this is the self-productive action of
nature. In the modern way of looking at life this conception becomes
lost in two different ways; either through a mechanical philosophy,
in which we always find as principle pressure, impulse, chemical
relationships and forces, or external relations generally—which
certainly seem to be inherent in nature, but not to proceed from the
nature of the body, seeing that they are an added, foreign appendage,
such as colour in a fluid; or else theological physics maintain the
thoughts of an understanding outside of the world to be the causes.
In the Kantian philosophy we for the first time have that conception
once more awakened in us, for organic nature at least; life has there
been made an end to itself. In Kant this indeed had only the subjective
form which constitutes the essence of the Kantian philosophy, in which
it seems as though life were only so determined by reason of our
subjective reasoning; but still the whole truth is there contained
that the organic creation is the self-maintaining. The fact that most
recent times have brought back the rational view of the matter into our
remembrance, is thus none else than a justification of the Aristotelian
Idea.
Aristotle also speaks of the end which is represented by organic nature
in itself, in relation to the means, of which he says (Phys. II. 8):
“If the swallow builds her nest, and the spider spreads her web, and
trees root themselves in the earth, for the sake of nutriment, there
is present in them a self-maintaining cause of this kind, or an end.”
For this instinctive action exhibits an operation of self-preservation,
as a means whereby natural existence becomes shut up and reflected
into itself. Aristotle then brings what is here said into relation
with general conceptions which he had earlier maintained (p. 138):
“Since nature is twofold as matter and form, but since the latter is
end, and the rest are on account of the end, this is final cause.”
For the active form has a content, which, as content of potentiality,
contains the means which make their appearance as adapted for an end,
_i.e._ as moments established through the determinate Notion. However
much we may, in the modern way of regarding things, struggle against
the idea of an immanent end, from reluctance to accept it, we must, in
the case of animals and plants, acknowledge such a conception, always
re-establishing itself in another. For example, because the animal
lives in water or in air, it is so constructed that it can maintain
its existence in air or water; thus it requires water to explain the
gills of fishes; and, on the other hand, because the animal is so
constructed, it lives in water. This activity in transformation thus
does not depend in a contingent way on life; it is aroused through the
outward powers, but only in as far as conformity with the soul of the
animal permits.
In passing, Aristotle here (Phys. II. 8) makes a comparison between
nature and art, which also connects what results with what goes
before, in accordance with ends. “Nature may commit an error as well
as art; for as a grammarian sometimes makes a mistake in writing, and
a physician in mixing a medicinal draught, nature, too, sometimes does
not attain its ends. Its errors are monstrosities and deformities,
which, however, are only the errors of that which operates for an
end. In the production of animals and plants, an animal is not at
first produced, but the seed, and even in it corruption is possible.”
For the seed is the mean, as being the not as yet established,
independent, indifferent, free actuality. In this comparison of nature
with art we ordinarily have before us the external adaptation to end,
the teleological point of view, the making for definite ends. And
Aristotle declaims against this, while he remarks that if nature is
activity for a certain end, or if it is the implicitly universal, “it
is absurd to deny that action is in conformity with end, because that
which moves cannot be seen to have deliberated and considered.” The
understanding comes forward with the determination of this end, and
with its instruments and tools, to operate on matter, and we carry
this conception of an external teleology over into nature. “But art
also,” says Aristotle, “does not deliberate. If the form of a ship
were the particular inward principle of the timber, it would act as
nature prompted. The action of nature is very similar to the exercise
of the art whereby anyone heals himself.” Through an inward instinct
the animal avoids what is evil, and does what is good for him; health
is thus essentially present to him, not as a conscious end, but as an
understanding which accomplishes its ends without conscious thought.
As Aristotle has hitherto combated an external teleology, he directs
another equally applicable remark (Phys. II. 9) against merely external
necessity, and thus we come to the other side, or to how necessity
exists in nature. He says in this regard: “Men fancy that necessity
exists in this way in generation, just as if it were thought that a
house existed from necessity, because heavy things were naturally
carried downwards, and light things upwards, and that, therefore, the
stones and foundation, on account of their weight, were under the
earth, and the earth, because it was lighter, was further up, and the
wood in the highest place because it is the lightest.” But Aristotle
thus explains the facts of the case. “The house is certainly not made
without these materials, but not on account of, or through them (unless
the material so demands), but it is made for the sake of concealing and
preserving certain things. The same takes place in everything which
has an end in itself; for it is not without that which is necessary to
its nature, and yet it is not on account of this, unless the matter
so demands, but on account of an end. Hence the necessary is from
hypothesis only, and not as end, for necessity is in matter, but end
is in reason (λόγῳ). Thus it is clear that matter and its movement are
necessity in natural things; both have to be set forth as principle,
but end is the higher principle.” It undoubtedly requires necessity,
but it retains it in its own power, does not allow it to give vent
to itself, but controls external necessity. The principle of matter
is thus turned into the truly active ground of end, which means the
overthrow of necessity, so that that which is natural shall maintain
itself in the end. Necessity is the objective manifestation of the
action of its moments as separated, just as in chemistry the essential
reality of both the extremes—the base and the acid—is the necessity of
their relation.
This is the main conception of Aristotelian Physics. Its further
development concerns the conceptions of the different objects of
nature, a material for speculative philosophy which we have spoken
of above (pp. 153-155), and regarding which Aristotle puts before us
reflections both difficult and profound. Thus he at first (Phys. III.
1-3) proceeds from this point to movement (κίνησις), and says that it
is essential that a philosophy of nature should speak of it, but that
it is difficult to grasp; in fact, it is one of the most difficult
conceptions. Aristotle thus sets to work to understand movement in
general, not merely in space and time, but also in its reality; and
in this sense he calls it “the activity of an existent thing which
is in capacity, so far as it is in capacity.” He explains this thus:
“Brass is in capacity a statue; yet the motion to become a statue
is not a motion of the brass so far as it is brass, but a motion of
itself, as the capacity to become a statue. Hence this activity is
an imperfect one (ἀτελής),” _i.e._ it has not its end within itself,
“for mere capacity, whose activity is movement, is imperfect.” The
absolute substance, the moving immovable, the existent ground of
heaven which we saw as end, is, on the contrary, both activity itself
and the content and object of activity. But Aristotle distinguishes
from this what falls under the form of this opposition, “That moving
is also moved which has movement as a capacity, and whose immobility
is rest. That in which movement is present has immobility as rest;
for activity in rest, as such, is movement.” That is to say, rest is
capacity for motion. “Hence movement is the activity of that which is
movable (κινητοῦ),[93] so far as it is movable; but this happens from
the contact of that which is motive (κινητικοῦ), so that at the same
time it is posited as passive likewise. But that which moves always
introduces a certain form or end (εἶδος), either this particular thing
(τόδε), or a quality or a quantity, which is the principle and cause of
the motion when it moves; thus man, as he is in energy, makes man from
man as he is in capacity. Thus, too, it is evident that movement is in
the movable thing: for it is the activity of this, and is derived from
that which is motive. The activity of that which is motive is likewise
not different, for both are necessarily activity. It is motive because
it has the capacity for being so; but it causes motion because it
energizes. But it is the energetic of the moveable (ἔστιν ἐνεργητικὸν
τοῦ κινετοῦ), so that there is one energy of both; just as the relation
between one and two is the same as that between two and one, and there
also is the same relation between acclivity and declivity, so the way
from Thebes to Athens is the same as from Athens to Thebes. Activity
and passivity are not originally (κυρίως) the same, but in what they
are inherent, in motion, they are the same. In Being (τῷ εἶναι) they
are identical, but activity, in so far as it is activity of this in
this” (what is moved), “and the activity of this from this” (what
moves), “is different as regards its conception (τῷ λόγῳ).” Aristotle
subsequently deals with the infinite (Phys. III. 4-8).
“In like manner it is necessary,” says Aristotle (Phys. IV. 1-5), “that
the natural philosopher should consider the subject of place (τόπος).”
Here come various definitions and determinations under which space
generally and particular space or place appear. “Is place a body? It
cannot be a body, for then there would be in one and the same, two
bodies. Again, if it is the place and receptacle (χώρα) of this body,
it is evident that it is so also of the superficies and the remaining
boundaries; but the same reasoning applies to these, for where the
superficies of water were before, there will now be the superficies
of air,” and thus the places of both superficies would be in one.
“But in truth there is no difference between the point and the place
of the point, so that if place is not different from the other forms
of limitation, neither is it something outside of them. It is not an
element, and neither consists of corporeal nor of incorporeal elements,
for it possesses magnitude, but not body. The elements of bodies
are, however, themselves bodies, and no magnitude is produced from
intelligible elements. Place is not the material of things, for nothing
consists of it—neither the form, nor the Notion, nor the end, nor the
moving cause; and yet it is something.” Aristotle now determines place
as the first unmoved limit of that which is the comprehending: it
comprehends the body whose place it is, and has nothing of the thing
in itself; yet it co-exists with the thing, because the limits and
the limited co-exist. The uttermost ends of what comprehends and of
what is comprehended are identical, for both are bounds; but they are
not bounds of the same, for form is the boundary of the thing, place
is that of the embracing body. Place, as the comprehending, remains
unchangeably passive while the thing which is moved is moved away; from
which we see that place must be separable from the thing. Or place,
according to Aristotle, is the boundary, the negation of a body, the
assertion of difference, of discretion; but it likewise does not merely
belong to this body, but also to that which comprehends. There is thus
no difference at all, but unchangeable continuity. “Place is neither
the universal (κοινός) in which all bodies are” (heaven), “nor the
particular (ἴδιος), in which they are as the first (πρώτῳ).” Aristotle
also speaks of above and below in space, in relation to heaven as that
which contains, and earth as what is beneath. “That body, outside of
which is a comprehending body, is in space. But the whole heavens are
not anywhere, since no body comprehends them. Outside the universe
nothing is, and hence everything is in the heavens, for the heavens
are the whole. Place, however, is not the heavens, but its external
quiescent boundary which touches the body moved. Hence the earth is in
water, water in air, air in ether, but ether in the heavens.”
From this point Aristotle goes on (Phys. IV. 6, 7) to empty space, in
which an old question is involved which physicists even now cannot
explain: they could do so if they studied Aristotle, but as far as they
are concerned there might have been no thought nor Aristotle in the
world. “Vacuum, according to ordinary ideas, is a space in which there
is no body, and, fancying that all Being is body, they say that vacuum
is that in which there is nothing at all. The conception of a vacuum
has its justification for one thing in the fact that a vacuum,” the
negative to an existent form, “is essential to motion; for a body could
not move in a plenum,” and in the place to which it does move there
must be nothing. “The other argument in favour of a vacuum is found
in the compression of bodies, in which the parts press into the empty
spaces.” This is the conception of varying density and the alteration
of the same, in accordance with which an equal weight might consist
of an equal number of parts, but these, as being separated by vacuum,
might present a greater volume. Aristotle confutes these reasonings
most adroitly, and first of all in this way; “The plenum could be
changed, and bodies could yield to one another even if no interval of
vacuum separated them. Liquids as well as solids are not condensed into
a vacuum; something that they contained is expelled, just as air is
expelled if water is compressed.”
Aristotle deals more thoroughly, in the first place (Phys. IV. 8), with
the erroneous conception that the vacuum is the cause of movement.
For, on the one hand, he shows that the vacuum really abolishes
motion, and consequently in vacuum a universal rest would reign. He
calls it perfect indifference as to the greater or less distance to
which a thing is moved; in vacuum there are no distinctions. It is
pure negation without object or difference; there is no reason for
standing still or going on. But body is in movement, and that, indeed,
as distinguished; it has a positive relation, and not one merely to
nothing. On the other hand, Aristotle refutes the idea that movement
is in vacuum because compression is possible. But this does not happen
in a vacuum; there would be established in it not one movement, but
a movement towards all sides, a general annihilation, an absolute
yielding, where no cohesion would remain in the body. “Again, a weight
or a body is borne along more swiftly or more slowly from two causes;
either because there is a difference in that through which it is borne
along, as when it moves through air or water or earth, or because that
which is borne along differs through excess of weight or lightness.” As
regards difference of movement on account of the first difference—that
in the density of the medium—Aristotle says: “The medium through which
the body is borne along is the cause of the resistance encountered,
which is greater if the medium is moving in a contrary direction (and
less if it is at rest); resistance is increased also if the medium is
not easily divided. The difference in velocity is in inverse ratio to
the specific gravity of the medium, air and water, so that if the
medium has only half the density, the rate of progress will be double
as quick. But vacuum has to body no such relation of differences
of specific gravity. Body can no more contain a vacuum within its
dimensions than a line can contain a point, unless the line were
composed of points. The vacuum has no ratio to the plenum.” But as to
the other case, the difference in weight and lightness, which has to
be considered as being in bodies themselves, whereby one moves more
quickly than another through the same space: “this distinction exists
only in the plenum, for the heavy body, by reason of its power, divides
the plenum more quickly.” This point of view is quite correct, and it
is mainly directed against a number of conceptions that prevail in our
physics. The conception of equal movement of the heavy and the light,
as that of pure weight, pure matter, is an abstraction, being taken as
though they were inherently like, only differing through the accidental
resistance of the air.
Aristotle (Phys. IV. 9) now comes to the second point, to the proof of
the vacuum because of the difference in specific gravity. “Many believe
that the vacuum exists because of the rare and the dense;” the former
is said to be a rare body, and the latter a perfect continuity; or
they at least differ quantitatively from one another through greater
or less density. “For if air should be generated from a quantity of
water, a given quantity of water must produce a quantity of air the
same in bulk, or there must necessarily be a vacuum; for it is only
on the hypothesis of a vacuum that compression and rarefaction are
explicable. Now if, as they say, the less dense were that which has
many separate void spaces, it is evident that since a vacuum cannot
be separated any more than a space can have intervals, neither can
the rare subsist in this manner. But if it is not separable, and yet
a vacuum is said to exist in the body, in the first place movement
could thus only be upwards; for the rare is the light, and hence they
say that fire is rare,” because it always moves upwards. “In the
next place the vacuum cannot be the cause of motion as that in which
something moves, but must resemble bladders that carry up that which
adheres to them. But how is it possible that a vacuum can move, or that
there can be a place where there is a vacuum? For that into which it
is carried would be the vacuum of a vacuum. In short, as there can be
no movement in vacuum, so also a vacuum cannot move.” Aristotle set
against these ideas the true state of matters, and states generally the
ideal conception of nature: “that the opposites, hot and cold, and the
other physical contraries, have one and the same matter, and that from
what is in capacity that which is in energy is produced; that matter
is not separable though it is different in essence[94] (τῷ εἶναι),
and that it remains one and the same in number (ἀριθμῷ) even if it
possesses colour, or is hot and cold. And again, the matter of a small
body and a large is the same, because at one time a greater proceeds
from a smaller, and at another time a smaller from a greater. If air is
generated from water it is expanded, but the matter remains the same
and without taking to itself anything else; for that which it was in
capacity it becomes in actuality. In a similar way if air is compressed
from a greater into a less volume, the process will be reversed, and
air will similarly pass into water, because the matter which is in
capacity both air and water, also becomes both.” Aristotle likewise
asserts that increase and decrease of warmth, and its transition into
cold, is no addition or otherwise of warm matter, and also one and the
same is both dense and rare. This is very different from the physical
conceptions which assert more or less matter to correspond with more
or less density, thus comprehending the difference in specific weight
as the external addition of matter. Aristotle, on the contrary, takes
this dynamically, though certainly not in the sense in which dynamics
are to-day understood, viz. as an increase of intensity or as a
degree, for he accepts intensity in its truth as universal capacity.
Undoubtedly the difference must also be taken as a difference in
amount, but not as an increase and decrease, or as an alteration in the
absolute quantity of the matter. For here intensity means force, but
again not as being a thing of thought separated from matter, but as
indicating that if anything has become more intensive, it has had its
actuality diminished, having, however, according to Aristotle, attained
to a greater capacity. If the intensity is again directed outwards,
and compared with other things, it undoubtedly becomes degree, and
therefore magnitude immediately enters in. It then is indifferent
whether greater intension or greater extension is posited; more air is
capable of being warmed to the same degree as less, through the greater
intensity of the warmth; or the same air can thereby become intensively
warmer.