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.
As regards the investigation of time, Aristotle remarks (Phys. IV. 10, 11, 13) that if time is externally (exoterically, ἐξωτερικῶς) regarded, we are inevitably led to doubt (διαπορῆσαι) whether it has any being whatever, or whether it has bare existence, as feeble (μόλις καὶ ἀμυδρῶς) as if it were only a potentiality. “For one part of it was and is not: another part will be and is not as yet; but of these parts infinite and everlasting (ἀεὶ λαμβανόμενος), time is composed. But it now appears that time, if composed of things that are not, may be incapable of existence. And also as regards everything divisible, if it exists, either some or all of its parts must be. Time is certainly divisible; but some of the parts are past, others are future, and no part is present. For the _now_ is no part, since a part has a measure, and the whole must consist of the parts; but time does not appear to consist of the Now.” That is to say, because the Now is indivisible, it has no quantitative determination which could be measured. “Besides it is not easy to decide whether the Now remains, or always becomes another and another. Again, time is not a movement and change, for movement and change occur in that which is moved and changed, or accompany time in its course; but time is everywhere alike. Besides change is swifter and slower, but time is not. But it is not without change and motion” (which is just the moment of pure negativity in the same) “for when we perceive no change, it appears as if no time had elapsed, as in sleep. Time is hence in motion but not motion itself.” Aristotle defines it thus: “We say that time is, when we perceive the before and after in movement; but these are so distinguished that we apprehend them to be another and another, and conceive that there is something between, as a middle. Now when we understand that the extremes of the conclusion are different from the middle, and the soul says that the Now has two instants, the one prior and the other posterior, then we say that this is time. What is determined through the Now, we call time, and this is the fundamental principle. But when we are sensible of the Now as one, and not as a prior and posterior in motion, nor as the identity of an earlier or later, then there does not appear to us to have been any time, because neither was there any motion.” Tedium is thus ever the same. “Time is hence the number of motion, according to priority and posteriority; it is not motion itself, unless so far as motion has number. We judge of the more or less through number, but of a greater or less motion by time. But we call number that which can be numbered, as well as that with which we number; but time is not the number with which we number, but that which is numbered, and, like motion, always is changing. The Now is, which is the unity of number, and it measures time. The whole of time is the same, for the Now which was is the same” (universality as the Now destroyed) “but in Being it is another. Time thus is through the Now both continuous (συνεχής) and discrete (διῇρηται). It thereby resembles the point, for that also is the continuity of the line and its division, its principle and limit; but the Now is not an enduring point. As continuity of time the Now connects the past and the future, but it likewise divides time in capacity,” the Now is only divisibility and the moments only ideal. “And in as far as it is such, it is always another; but, in as far as it unites, it is ever one and the same. Similarly, in as far as we divide the line, other and yet other points always arise for thought; but in as far as it is one, there is only one point. Thus the Now is both the division of time in capacity, and the limit and union of both” _i.e._ of the prior and posterior. The universally dividing point is only one as actual; but this actual is not permanently one, but ever and again another, so that individuality has universality, as its negativity, within it. “But division and union are the same, and similarly related; however their Notion (τὸ εἶναι)[95] is different.” In one and the same respect the absolute opposite of what was posited is immediately set forth as existent; in space, on the other hand, the moments are not set forth as existent, but in it first appears this being and its motion and contradiction. Thus the identity of the understanding is not a principle with Aristotle, for identity and non-identity to him are one and the same. Because the Now is only now, past and future are different from it, but they are likewise necessarily connected in the Now, which is not without before and after; thus they are in one, and the Now, as their limit, is both their union and their division.
Aristotle (Phys. V. 1) then goes on to movement as realized in a thing, to change (μεταβολή) or to the physical processes—while before we had pure movement. “In movement there is first something which moves, also something which is moved, and the time in which it is moved; besides these, that from which, and that into which it is moved.” (Cf. _supra_, p. 141.) “For all motion is from something and into something; but there is a difference between that which is first moved and that into which and from which it is moved, as, for instance, wood, warmth and cold. The motion is in the wood and not in the form; for neither form nor place, nor quantity moves or is moved, but” (in the order in which they follow) “there is that which is moved and that which moves, and that into which it is moved. That to which movement is made, more than that out of which movement is made, is named change. Hence to pass into non-being is also change, although what passes away is changed from Being: and generation is a mutation into Being, even though it is from non-being.” The remark is to be interpreted as meaning that for the first time in real becoming motion, _i.e._ in change, the relation _whereto_ enters, while the relation _wherefrom_ is that in which change is still the mere ideal motion. Besides this first form of difference between motion and change, Aristotle further gives another, since he divides change into three: “into change from a subject (ἐξ ὑποκειμένον) into a subject; or from a subject into a non-subject; or from a non-subject into a subject.” The fourth, “from a non-subject into a non-subject,” which may also appear in the general division, “is no mutation, for it contains no opposition.” It may certainly be merely thought or ideal, but Aristotle indicates the actual phenomenon. “The mutation from a non-subject into a subject is generation (γένεσις); that from a subject into a non-subject is corruption (φθορά); that from a subject into a subject, is motion as such;” because that which is transformed remains the same, there is no becoming-another of the actual, but a merely formal becoming-another. This opposition of the materialized motion as mutation, and of merely formal motion, is noteworthy.