by Aristotle
As to the thinkers who explain modification of property through the movement in the pores, if this is supposed to occur notwithstanding the fact that the pores are filled their postulate of pores is superfluous. For if the whole body suffers action under these conditions, it would suffer action in the same way even if it had no pores [10] but were just its own continuous self. Moreover, how can their account of vision through a medium be correct? It is impossible to penetrate the transparent bodies at their contacts or through their pores if every pore be full. For how will that differ from having no pores at all? The body will be uniformly full throughout. But, [15] further, even if these passages, though they must contain bodies, are void, the same consequence will follow once more. And if they are too minute to admit any body, it is ridiculous to suppose there is a ‘minute’ void and yet to deny the existence of a big one of whatever size, or to imagine ‘the void’ means anything else than a body’s [20] place—whence it clearly follows that to every body there will correspond a void of equal bulk.
As a general criticism we must urge that to postulate pores is superfluous. For if the agent produces no effect by touching the patient, neither will it produce any by passing through its pores. On the other hand, if it acts by contact, then—even without pores—some things will suffer action and others will act, provided they are by nature adapted for reciprocal action and passion. Our arguments have shown [25] that it is either false or futile to advocate pores in the sense in which some thinkers conceive them. But since bodies are divisible through and through the postulate of pores is ridiculous; for, qua divisible, a body can fall into separate parts.
9 · Let us explain the way in which things possess the power of generating, [30] and of acting and suffering action; and let us start from the principle we have often enunciated. For, assuming, the distinction between that which is potentially and that which is actually such-and-such, it is the nature of the first, in so far as it is what it is, to suffer action through and through, not merely to be susceptible in some parts while insusceptible in others. But its susceptibility varies in degree, according as it is more or less such-and-such, and one would be more justified in speaking of pores in this connexion—just as in metals there are veins of susceptible stuff stretching continuously through the substance.
[327a1] So long, indeed, as any body is naturally coherent and one, it is insusceptible. So, too, bodies are insusceptible so long as they are not in contact either with one another or with other bodies which are by nature such as to act and suffer action. (To illustrate my meaning: Fire heats not only when in contact, but also from a [5] distance. For the fire heats the air, and the air—being by nature such as both to act and suffer action—heats the body.) But the supposition that a body suffers action in some parts, but not in others ἡis only possible for those who hold an erroneous view concerning the divisibility of magnitudes. For usά12 the following account results from the distinctions we established at the beginning. For if magnitudes are not divisible through and through—if, on the contrary, there are indivisible solids or planes—then indeed nothing would be susceptible through and through: but neither would anything be continuous. Since, however, this is false, i.e. since every body is [10] divisible, there is no difference between having been divided into parts which remain in contact and being divisible. For if a body can be separated at the contacts (as some say), then, even though it has not yet been divided, it will be in a state of dividedness—for it can be divided, since nothing impossible results. And in general it is absurd that passion should occur in this manner only, viz. by the bodies being [15] split. For this theory abolishes alteration; but we see the same body liquid at one time and solid at another, without losing its continuity. It has suffered this change not by division and composition, nor yet by ‘turning’ and ‘intercontact’ as Democritus asserts; for it has passed from the liquid to the solid state without any [20] reordering or transposition in its nature. Nor are there contained within it those hard (i.e. congealed) particles indivisible in their bulk; on the contrary, it is liquid—and again, solid and congealed—uniformly all through. This theory, it must be added, makes growth and diminution impossible also. For if there is to be apposition (instead of the growing thing having changed as a whole, either by the admixture of something or by its own transformation), increase of size will not have [25] resulted in any and every part.
So much, then, to establish that things generate and are generated, act and suffer action, reciprocally; and to distinguish the way in which these processes can occur from the (impossible) way in which some say they occur.
10 · But we have still to explain combination, for that was the third of the [30] subjects we originally proposed to discuss. Our explanation will proceed on the same method as before. We must inquire: What is combination, and what is that which can combine? Of what things, and under what conditions, is combination a property? And, further, does combination exist in fact, or is it false to assert its existence?
For, according to some thinkers, it is impossible for one thing to be combined with another. They argue that if the combined constituents continue to exist and [327b1] are unaltered, they are no more combined now than they were before, but are in the same condition; while if one has been destroyed, the constituents have not been combined—on the contrary, one constituent is and the other is not, whereas combination demands uniformity of condition in them both; and on the same principle even if both the combining constituents have been destroyed as the result [5] of their coalescence, they cannot be combined since they have no being at all.
What we have in this argument is, it would seem, a demand for the precise distinction of combination from coming-to-be and passing-away (for it is obvious that combination, if it exists, must differ from these processes) and for the precise distinction of the combinable from that which is such as to come-to-be and [10] pass-away. As soon, therefore, as these distinctions are clear, the difficulties raised by the argument would be solved.
Now we do not speak of the wood as combined with the fire, nor of its burning as a combining either of its particles with one another or of itself with the fire: what we say is that the fire is coming-to-be, but the wood is passing-away. Similarly, we [15] speak neither of the food as combining with the body, nor of the shape as combining with the wax and thus fashioning the lump. Nor can body combine with white, nor (to generalize) properties and states with things; for we see them persisting unaltered. But again white and knowledge cannot be combined either, nor anything else which is not separable. (Indeed, this is a blemish in the theory of those who [20] assert that once all things were together and combined. For not everything can combine with everything. On the contrary, both of the constituents that are combined must originally have existed in separation; but no property can have separate existence.)
Since, however, some things are potentially while others are actually, the constituents can be in a sense and yet not-be. The compound may be actually other [25] than the constituents from which it has resulted; nevertheless each of them may still be potentially what it was before they were combined, and both of them may survive undestroyed. (For this was the difficulty that emerged in the previous argument; and it is evident that the combining constituents not only coalesce, having formerly existed in separation, but also can again be separated out from the compound.) The constituents, therefore, neither persist actually, as body and white [30] persist; nor are they destroyed (either one of them or both), for their potentiality is preserved. Hence these difficulties may be dismissed; but the problem immediately connected with them—whether combination is something relative to perception—must be set out and discussed.
When the combining constituents have been divided into parts so small, and have been juxtaposed in such a manner, that perception fails to discriminate them one from another, have they then been combined? Or is it rather when any and [328a1] every part of one constituent is juxtaposed to a part of the other? The term, no doubt, is applied in the latter
sense: we speak, e.g., of wheat having been combined with barley when each grain of the one is juxtaposed to a grain of the other. But every body is divisible and therefore, since body combined with body is uniform, any [5] and every part of each constituent ought to be juxtaposed to a part of the other.
No body, however, can be divided into its least parts; and composition is not identical with combination, but other than it. Thus it is clear that so long as the constituents are preserved in small particles, we must not speak of them as combined. (For this will be a composition instead of a blending or combination; nor will the part exhibit the same ratio between its constituents as the whole. But we [10] maintain that, if combination has taken place, the compound must be uniform—any part of such a compound being the same as the whole, just as any part of water is water; whereas, if combination is composition of the small particles, nothing of the kind will happen. On the contrary, the constituents will only be combined relatively to perception; and the same thing will be combined to one percipient, if his [15] sight is not sharp—while to the eye of Lynceus nothing will be combined.) Clearly too we must not speak of the constituents as combined in virtue of a division such that any and every part of each is juxtaposed to a part of the other; for it is impossible for them to be thus divided. Either, then, there is no combination, or we have still to explain the manner in which it can take place.
Now, as we maintain, some things are such as to act and others such as to suffer action from them. Moreover, some things—viz. those which have the same [20] matter—reciprocate, i.e. are such as to act upon one another and to suffer action from one another; while other things, viz. agents which have not the same matter as their patients, act without themselves suffering action. Such agents cannot combine—that is why neither the art of healing nor health produces health by combining with the bodies of the patients. Amongst those things, however, which are both active and passive, some are easily divisible. Now if a great quantity (or a large bulk) of one of these materials be brought together with a little (or with a [25] small piece) of another, the effect produced is not combination, but increase of the dominant; for the other material is transformed into the dominant. (That is why a drop of wine does not combine with ten thousand gallons of water; for its form is dissolved, and it is changed so as to merge in the total volume of water.) On the other hand, when there is a certain equilibrium between their powers, then each of them changes out of its own nature towards the dominant; yet neither becomes the [30] other, but both become an intermediate with properties common to both.
Thus it is clear that only those agents are combinable which involve a contrariety—for these are such as to suffer action reciprocally. And, further, they combine more freely if small pieces of each of them are juxtaposed. For in that condition they change one another more easily and more quickly; whereas this effect takes a long time when agent and patient are present in bulk.
Hence, amongst the divisible susceptible materials, those whose shape is [328b1] readily adaptable have a tendency to combine; for they are easily divided into small particles, since that is precisely what being readily adaptable in shape implies. For instance, liquids are the most combinable of all bodies—because, of all divisible materials, the liquid is most readily adaptable in shape, unless it be viscous. Viscous liquids, it is true, produce no effect except to increase the bulk. But when one of the [5] constituents is alone susceptible—or superlatively susceptible, the other being susceptible in a very slight degree—the compound resulting from their combination is either no greater in volume or only a little greater. This is what happens when tin is combined with bronze. For some things display a hesitating and ambiguous attitude towards one another—showing a slight tendency to combine and also an [10] inclination to behave as receptive matter and form. The behaviour of these metals is a case in point. For the tin almost vanishes, behaving as if it were an immaterial property of the bronze: having been combined, it disappears, leaving no trace except the colour it has imparted to the bronze. The same phenomenon occurs in other instances too.
It is clear, then, from the foregoing account, that combination occurs, what it [15] is, to what it is due, and what kind of thing is combinable. The phenomenon depends upon the fact that some things are such as to be reciprocally susceptible and readily adaptable in shape, i.e. easily divisible. For such things can be combined without its being necessary either that they should have been destroyed or that they should survive absolutely unaltered; and their combination need not be a composition, nor [20] merely relative to perception. On the contrary: anything is combinable which, being readily adaptable in shape, is such as to suffer action and to act; and it is combinable with another thing similarly characterized (for the combinable is relative to the combinable); and combination is unification of the combinables, resulting from their alteration.
BOOK II
1 · We have explained under what conditions combination, contact, and action and passion are attributable to the things which undergo natural change. Further, we have discussed unqualified coming-to-be and passing-away, and explained under what conditions they occur, in what subject, and owing to what [30] cause. Similarly, we have also discussed alteration, and explained what altering is and how it differs from coming-to-be and passing-away. But we have still to investigate the so-called elements of bodies.
For coming-to-be and passing-away occur in naturally constituted substances only given the existence of sensible bodies. But as to the matter which underlies these perceptible bodies, some maintain it is single, supposing it to be, e.g., Air or Fire, or an intermediate between these two (but still a body with a separate [329a1] existence). Others, on the contrary, postulate more than one—ascribing to their association and dissociation, or to their alteration, the coming-to-be and passing-away of things. (Some, for instance, postulate Fire and Earth; some add Air, making three; and some, like Empedocles, reckon Water as well, thus postulating four.)
[5] Now we may agree that the primary materials, whose change (whether it be association and dissociation or a process of another kind) results in coming-to-be and passing-away, are rightly described as principles or elements. But those thinkers are in error who postulate, beside the bodies we have mentioned, a single [10] matter—and that a corporeal and separable matter. For this body cannot possibly exist without a perceptible contrariety—this ‘Boundless’, which some thinkers identify with the principle, must be either light or heavy, either cold or hot. And what Plato has written in the Timaeus13 is not based on any precisely-articulated [15] conception. For he has not stated clearly whether his ‘Omnirecipient’ exists in separation from the elements; nor does he make any use of it. He says, indeed, that it is a substratum prior to the so-called elements—underlying them, as gold underlies the things that are fashioned of gold. (And yet this comparison, if thus expressed, is itself open to criticism. Things which come-to-be and pass-away [20] cannot be called by the name of the material out of which they have come-to-be: it is only the results of alteration which retain the name. However, he actually says that far the truest account is to affirm that each of them is gold.) Nevertheless he carries his analysis of the elements—solids though they are—back to planes, and it is impossible for ‘the Nurse’ (i.e. the primary matter) to be identical with the planes.
Our own doctrine is that although there is a matter of the perceptible bodies (a [25] matter out of which the so-called elements come-to-be), it has no separate existence, but is always bound up with a contrariety. A more precise account of this has been given in another work;14 we must, however, give a detailed explanation of the primary bodies as well, since they too are similarly derived from the matter. We must reckon as a principle and as primary the matter which underlies, though it is [30] inseparable from, the contrary qualities; for the hot is not matter for the cold nor the cold for the hot, but the substratum is matter for them both. Thus as principles we have firstly that which is potentially perceptible body, secondly the contrarieties (I mean, e
.g., heat and cold), and thirdly Fire, Water, and the like. For these bodies change into one another (they are not immutable as Empedocles and other thinkers [329b1] assert, since alteration would then have been impossible), whereas the contrarieties do not change.
Nevertheless, even so the question remains: What sorts of contrarieties, and how many of them, are to be accounted principles of body? For all the other thinkers assume and use them without explaining why they are these or why they [5] are just so many.
2 · Since, then, we are looking for principles of perceptible body; and since perceptible is equivalent to tangible, and tangible is that of which the perception is touch, it is clear that not all the contrarieties constitute forms and principles of body, but only those which correspond to touch. For it is in accordance with a [10] contrariety—a contrariety, moreover, of tangible qualities—that the primary bodies are differentiated. That is why neither whiteness and blackness, nor sweetness and bitterness, nor similarly any of the other perceptible contrarieties either, constitutes an element. And yet vision is prior to touch, so that its object also is prior. The object of vision, however, is a quality of tangible body not qua tangible, [15] but qua something else—even if it is naturally prior.
Accordingly, we must segregate the tangible differences and contrarieties, and distinguish which amongst them are primary. Contrarieties correlative to touch are the following: hot-cold, dry-moist, heavy-light, hard-soft, viscous-brittle, rough-smooth, [20] coarse-fine. Of these heavy and light are neither active nor susceptible. Things are not called heavy and light because they act upon, or suffer action from, other things. But the elements must be reciprocally active and susceptible, since they combine and are transformed into one another. On the other hand, hot and cold, and dry and moist, are terms, of which the first pair implies power to act and [25] the second pair susceptibility. Hot is that which associates things of the same kind (for dissociating, which people attribute to Fire as its function, is associating things of the same class, since its effect is to eliminate what is foreign), while cold is that which brings together, i.e. associates, homogeneous and heterogeneous things alike. [30] And moist is that which, being readily adaptable in shape, is not determinable by any limit of its own; while dry is that which is readily determinable by its own limit, but not readily adaptable in shape.