CORRESPONDENCE WITH DES BOSSES
Translation © George MacDonald Ross, 1974–1999
1. Leibniz to Des Bosses, 17th March 1707
[304] . . . The arguments against an actual infinity suppose that if this were admitted there would be an infinite number, and likewise that all infinites are equal. But it needs to be remembered that in fact an infinite aggregate is neither a single whole or endowed with size, nor is it commensurable with any number. Strictly speaking, instead of talking about an infinite number one should say that there are more things than can be expressed by any number; or instead of an infinite straight line, that a straight line extends beyond any determinable length, so that there is always a longer and longer line. It is essential to a number, a line, or any sort of whole that it is bounded by limits. Hence even if [305] the world were infinite in size, it would not be a single whole, nor would it be possible to think of God as the soul of the world (as did some of the ancients), not only because he is the cause of the world, but also because such a world would not be a single body, nor could it be considered as an animal; and hence its unity would be merely verbal. So we are talking elliptically when we ascribe unity to cases where there are more things than can be included in a single determinable whole, and talk in terms of magnitude about something which does not have the properties of magnitude. For just as it cannot be said whether an infinite number is odd or even, so it cannot be said whether or not an infinite straight line is commensurable with any given line; so these ways of talking about infinity as if it were a single magnitude are simply inappropriate, and though they are based on an analogy, they cannot stand up if you examine them more closely. Only the absolute and indivisible infinite has true unity, namely God. And I think these remarks are sufficient to satisfy all the arguments against actual infinity. For it cannot be denied that the essences of all possible numbers actually exist, at least in the divine mind, and hence that the multitude of numbers is infinite.
Philosophically speaking, I am as much against infinitely small magnitudes (infinitesimals) as against infinitely large ones (infinituples). For I consider both to be creatures of the mind intended to avoid prolixity, and suitable for the purposes of calculation, as also are imaginary roots in algebra. On the other hand, I have shown that these expressions are very useful for brevity of thought and hence for the discovery of new truths, and that they cannot lead to error, since for ‘infinitely small’ it would be enough to substitute ‘as small as anyone would wish, for any error to be within any specified limits,’ from which it follows that there can be no error. It seems that Father Gouye, who objected to this, did not adequately understand what I meant.
But to turn from geometrical ideas to physical realities, I maintain that matter is actually broken into parts that are smaller than any size you could specify, i.e. that there is no part which is not in fact subdivided into others, subject to various different motions. This is required by the nature of matter, motion, and the whole structure of the universe, for physical, mathematical, and metaphysical reasons.
When I say that there is no part of matter which does not contain monads, I explain this by taking as an example the human body, or that of any other animal, of which all the solid or fluid parts in their turn contain within themselves other animals and vegetables. And I believe the same must again be said of every part of these living beings, and so on to infinity.
I think that no entelechy [n.1] is attached to any particular part of matter (secondary matter, that is), [n.2] [306] or, what comes to the same thing, to particular other partial entelechies. [n.3] For matter changes like a river, though the entelechy remains as long as the machine subsists. [n.4] A machine has an entelechy perfectly corresponding to it, and this machine contains other machines which do not correspond perfectly to the primary entelechy, but are endowed with their own entelechies corresponding to them perfectly, and separable from the original complete machine. Certainly scholastic philosophy also admits partial forms. So the same matter is subordinate to a multiplicity of forms, but in different ways according to the way it corresponds to them. But the situation is quite different if you mean primary matter, or ‘the primary passive power, primary subject,’ [n.5] that is, primitive passive power or the principle of resistance, which consists not in extension but in a striving towards extension, and completes entelechy or primitive active power, so as to result in a complete substance or monad, in which its modifications are contained virtually. Our understanding of the question is that matter in this sense, that is the principle of passivity, persists and remains with its entelechy, and thus secondary matter results from a multiplicity of monads, together with derivative forces, actions, and passions, [n.6] which are only beings by aggregation, and to that extent semi-mental entities, like the rainbow and other well-founded phenomena. But you can see that it does not follow from this that an infinitely small portion of matter (not that there is any such thing) can be assigned to any entelechy, even though we are liable to jump to such conclusions. To use an analogy: imagine a circle, and in this describe three other circles which are as large as possible and equal to each other, and in each new circle and the gap between the circles again three other equal circles as large as possible, and imagine this process carried to infinity. From this it does not follow that there is an infinitely small circle, or that there is a centre which has its own circle peculiar to it, in which no other circle is inscribed (which would contradict the original hypothesis).
My assertion that souls and animals do not die I shall explain by another analogy. Imagine that an animal is like a drop of oil and a soul like a point in the drop. If the drop is now scattered into bits, since each bit becomes in its turn another spherical drop, the point will exist in one of the new drops. In the same way, the animal will continue to exist in the part in which the soul remains, and which is most appropriate to the soul itself. And just as by its very nature a liquid immersed in another fluid strives after sphericity, so matter, which has been constructed by the infinitely wise author [of the universe], by its very nature always strives after order or organisation. Hence neither souls nor animals can be destroyed, even though they can become smaller and lost to view, so that the fact that they are alive is not apparent to us. There is no doubt that in coming into being and passing away nature observes definite laws, for none of the works of God [307] is without order. Besides, anyone who considers this opinion that animals are conserved must also consider my doctrine that there are infinitely many organs in an animal’s body, some enclosed in others, and hence that an animal machine and natural machines in general are completely indestructible. . . .
2. Leibniz to Des Bosses, 24th April 1709
[370] . . . .Now I come to the philosophical question. I am not prepared to state categorically whether or not the souls of animals were created exactly on the fourth day; at any rate innumerable entelechies must have been created right from the beginning; but all I wanted to explain was how new souls could exist without any new part of matter being created. And, unless I am mistaken, I managed to do this in my recent letter. But what I mean by ‘matter’ here is ‘mass’ or ‘secondary matter’, which has both extension and resistance. And taking ‘matter’ in this sense, I do not remember having said that any soul has its own matter peculiar to it; on the contrary, every part of an organic body contains other entelechies. However, it is true that a soul cannot move from one organic body to another, but always remains in the same organic body, and even death does not violate this law. But it should be noted that this organic body remains the same in the sense that Theseus’ ship or a river remains the same, i.e. in a perpetual flux, perhaps without it being possible to specify any portion of matter which always remains peculiar to the same animal or soul. If you were to consider the question more thoroughly, you might try to maintain that at least a certain point can be assigned to a soul. But a point is not a definite part of matter, nor could infinitely many points gathered together form extension. I prove this as follows:
Take a triangle ABC, and bisect its side AC at D, and AD at E, and AE at F, and AF at G, and so on. Suppose that this is done to infinity, then we have infinitely many triangles BCD, BDE, BEF, BFG, etc. But any of these can exist separately (if they are endowed with solidity so as to make bodies, or supposing initially that the triangle is a solid one, i.e. a pyramid). And thus each one will have its own vertex. Then imagine that they are all fitted together to make the complete pyramid or triangle ABC, and it is obvious that all those infinitely many vertices fitted together in this way will only make a single common vertex B. But if you are unwilling to talk in terms of infinitely many triangles, at least you can see that this is generally true of any number of triangles. Now, extension arises from position, but it adds continuity to position. Points have position, but neither possess nor compose continuity, nor can they exist by themselves. Therefore nothing prevents infinitely many points from continually coming into being or disappearing (or at least coinciding or being separated from each other) without any increase or diminution of matter and extension, since they are only modifications of it, i.e. not parts, but limits. On the other hand, I do not think it appropriate for us to think of souls as if they existed in points. [371] Perhaps someone would say that they exist in space only by virtue of the effects they have [on objects in space] (that is, in terms of the old theory of causal influence), or rather (in terms of the new theory of pre-established harmony) that they exist in space by virtue of their correspondence [with objects in space], and thus they are in the whole of the organic body which they animate. Now I do not deny a certain real metaphysical union between soul and organic body (as I have already said in my reply to Tournemine), by virtue of which it can be said that the soul is truly in the body. But because it cannot be explained in phenomenal terms, since it makes no difference to anything that happens at the phenomenal level, I can give no further distinct explanation of what it formally consists in. It is enough that it has something to do with correspondence. But you see that here I have so far said nothing about the union of the entelechy (or active principle) with primary matter (or passive power), but only about the union of the soul or the monad itself (the resultant of both these principles) with mass, i.e. with other monads.
But, you will ask, what are we to say about the primary matter itself which is proper to the soul? My answer is that it is certainly created together with the soul, i.e. that the monad is created as a whole. Does it not then follow that the quantity of primary matter is increased or diminished? I would admit this, since it is nothing but primitive passive power. So, you will say, mass too is increased. I admit that the number of monads is increased, and that mass is certainly the resultant of them; but not that extension and resistance, or phenomena, are increased, any more than when new points come into being. God could create infinitely many new monads, but without increasing mass, if he only used old monads for the organic body of the new monad. Mass is a real phenomenon, and nothing is changed in phenomena on account of the emergence of a new monad (except the phenomena which constitute the perceptions of the completely new monad), unless perhaps by a miracle. For our opinion should be that the old monads were already so ordained by God from the time of their original creation that their phenomena would at some time correspond to a monad yet to be created, unless we prefer to say that when God creates a new monad, he miraculously changes all the others to accommodate them to the new one, which is less likely.
But all of this tends to the conclusion that it is possible for God to create new monads. However, I do not state categorically that new monads are created by God. Rather I would consider that the contrary can be defended and is more probable, namely the theory of the pre-existence of monads. More defensible than the theory that rational souls are newly created [at conception] would be the theory that non-rational souls are ‘transcreated’ into rational ones, which would happen by the miraculous addition of the necessary degree of perfection. This is the position I defend in my treatise against Bayle, since it seems to me more probable than any sort of creation, and truer than traducianism. . . .[n.7]
[372] P.S. Many years ago, before my philosophy was sufficiently developed, I used to locate souls in points, and thus I thought that the multiplication of souls could be explained by traduction, in that many points can come into being from a single one, as the vertices of many triangles can be generated from the vertex of a single triangle by division. But on becoming more careful, I realised that this not only entangled us in innumerable difficulties, but that it involved a sort of category mistake. What belongs to extension is not to be attributed to souls, and their unity or multiplicity is not to be taken from the category of quantity, but from that of substance, that is, not from points, but from the primitive power of acting. But the proper action of the soul is perception, and the unity of the percipient depends on the interconnectedness with which the subsequent perceptions are derived from previous ones.
3. Leibniz to Des Bosses, 31st July 1709
[378] . . . If positions of monads are designated by modifications or terminations of parts of space, monads themselves are still not modifications of a continuous thing. [379] Mass and its diffusion result from monads, but space does not. For space, just like time, is an order, that is (in the case of space) the order of coexistence, which embraces possibles as well as actuals. From which it follows that it is something indefinite, like every continuum the parts of which do not actually exist, but can be adopted arbitrarily, just like the parts of unity, or fractions. If in the universe subdivisions of organic bodies into organic bodies were different, monads would be different, and likewise mass, even though the space it filled would be the same. That is, space is something continuous, but ideal; whereas mass is discrete, i.e. an actual multitude, or a being by aggregation, but composed of infinitely many units. In actuals, simples are prior to aggregates; in ideals, the whole is prior to the part. It was neglect of this consideration that gave rise to the notorious labyrinth of the continuum. . . .[n.8]
4. Leibniz to Des Bosses, 8th September 1709
[390] . . . Mass is nothing but a phenomenon, like a rainbow. If God creates a new soul, or rather a monad, and makes the pre-existing organisms come together into a new organic body, he will not thereby increase mass or the quantity of phenomenon, as is obvious. However, I suspect it is hardly likely that God would ever do this, since I see no necessity for it. Arguments about what it is possible for God to do are liable to be very tricky. . .
5. Leibniz to Des Bosses, 5th February 1712
[435] . . . If corporeal substance is something real over and above monads, [n.9] as a line is said to be something over and above points, it will have to be said that corporeal substance consists in some sort of union, or rather a real unifier superimposed on monads by God, and further that its primary matter arises from the union of the passive powers of the monads, i.e. their strivings towards [exigentia] extension (diffusion) and antitypy (resistance); and that its substantial form arises from the union of the monadic entelechies But it follows from this that it can pass in and out of being, and that it will pass out of being when those monads cease to be united, unless it is miraculously conserved by God. But in this case such a form will not be a soul, which is a simple and indivisible substance. And this form, just like matter, is in a perpetual flux, since it is impossible to designate any point actually in matter which keeps to the same place for more than a moment, and which is not moving away from every one of the points next to it. But a soul stays the same through all its changes as long as the subject remains the same, which is not the case with corporeal substance. So it will have to be said either that bodies are mere phenomena, in which case extension too will be nothing other than a phenomenon, and only monads will be real, and that the unity [of a body] is added to the phenomenon by the activity of the perceiving soul; or, if faith compels us to [believe in] corporeal substances, that their substantiality consists in that uniting reality which adds something absolute (and hence substantial), if fleeting, to the things to be united. And it is in the conversion of this that your transubstantiation would have to be found, for monads are not in fact ingredients of this added thing, but requisites, even though they are required for it not by an absolute and metaphysical necessity, but only by a natural need [exigentia]. Therefore, even if the substance of a body were changed, it would still be possible for its monads to remain and be the foundation of sensible phenomena. A non-modal accident [n.10] seems difficult to explain, and I do not understand it at all in the case of extension. What can be said is that although monads are not accidents, yet it is accidental to a uniting substance that it has monads (by natural necessity), in the same way as it is accidental to a body that it is touched by another body, without that body being an accident. The extension of body seems to be nothing other than the continuation of matter through the contiguity of its parts [partes extra partes], i.e. diffusion. But when the contiguity is supernaturally abolished, the extension which was accidental to the body as such will be abolished with it; and all that will remain is phenomenal extension based on monads, together with everything else which results from it, and which alone would exist, if there were not a uniting substance. If that substantial vinculum of monads were not present, all bodies, together with their qualities, would be nothing other than well-founded phenomena, like a rainbow or an image in a mirror, in a word, uninterrupted dreams with perfect [436] internal coherence; and in this alone would the reality of these phenomena consist. For it should no more be said of monads that they are parts of bodies, touch each other, or compose bodies, than it is legitimate to say this of points or souls. And a monad, as a soul, is as it were its own world, having no relation of dependence except with God. Therefore, if body is a substance, it consists in something that endows phenomena with more reality than results from their internal coherence.
But if you absolutely refuse to regard these Eucharistic accidents [n.11] as mere phenomena, it could be said . . . . [etc., etc., for two paragraphs]
. . . . However, to tell the truth, I would prefer to give a phenomenal explanation of the Eucharistic accidents; thus there will be no need of non-modal accidents, which I can make virtually no sense of. . . .
6. Preparatory study for the letter to Des Bosses of 5th February 1712
[438] If bodies are phenomena and logical constructions out of our perceptions, they will not be real, because of their appearing differently to different people. Therefore the reality of bodies, space, motion, and time seems to consist in the fact that they are phenomena of God, or the objects of his visionary knowledge. And the difference between how bodies appear to us and how they appear to God is rather like that between a perspective plan and a ground plan. For perspective plans are different according to the viewpoint of the observer, whereas a ground plan or a geometrical representation is unique. That is, God sees things exactly as they are according to geometrical truth, though he also knows how each thing will appear to every other thing, and thus contains all other appearances within himself in a more perfect way.
Further, God observes not only individual monads and the modifications of each and every monad, but also their relations; and it is in this that the reality of relations and truths consists. One of the most basic of these is duration (the order of successive things), and position (the order of co-existence), and communication (interactions), namely when we consider the ideal dependence of monads on each other, whereas position without anything in-between is presence. Apart from presence and communication there is connection, when things move together. It is through these [relations] that things seem to us to form unities, and it is in fact possible to express truths about such wholes which have validity even for God. But beyond these real relations another more perfect one can be conceived, through which a new unitary substance arises from a multiplicity of substances. And this will not be a simple resultant, i.e. it will not consist only of true or real relations, but will also add some new substantiality or substantial vinculum [bond], and will be the effect not just of the divine intellect, but also of the divine will [i.e. being more than a relation it will require a positive act of creation]. This addition to monads does not come about in any old fashion, otherwise any substances, even widely scattered ones, [439] could be united to form a new substance, and it would not be specifically restricted to contiguous bodies; but it is enough that it should unite those monads which are under the domination of a single monad, i.e. which form a single organic body or machine of nature. And in this consists the metaphysical vinculum between soul and body, which constitutes a single subject (analogous to this is the union of natures in Christ). And it is these that make something an intrinsic unity or a single subject. . . .
7. Leibniz to Des Bosses, 26th May 1712
[444] . . . If you say that what is added to monads to make a union [n.12] is not substantial, then a body cannot be said to be a substance; for in that case it will be a mere aggregate of monads, and I fear you will end up with mere phenomena of bodies. For in themselves monads do not even have position relative to each other — I mean real position, which would involve something more than just the order of phenomena Each one of them is a sort of separate world, and they are in mutual harmony through their phenomena, with no other interaction or connection as such.
If you call an accident whatever presupposes a complete substance in such a way that it cannot naturally exist without it, you do not explain what the essence of an accident consists in, or even how, in its supernatural state, it is to be distinguished from a substance. Aristotelians certainly recognise something substantial over and above monads, otherwise there would be no substances apart from monads in their philosophy. And monads are not the constituents of complete compound substances, since they do not make something that is a unity in itself, but only an aggregate, unless some sort of substantial vinculum is added. From harmony [i.e. the coherence of our experiences], it cannot be proved that there is anything other than phenomena in bodies. For other considerations show that the harmony of the phenomena in souls is not the result of the influence of bodies, but that it is pre-established. And this would be sufficient if only souls, i.e. monads, existed; in which case all real extension would also disappear, let alone motion, the reality of which would be reduced to mere alterations of phenomena. . . .
8. Leibniz to Des Bosses, 16th June 1712
[450] . . . . The explanation of all phenomena by means of nothing but the mutually harmonious perceptions of monads, without any reference to corporeal substance, I consider useful for the fundamental inspection of things. In this manner of exposition, space becomes the order of co-existent phenomena and time of successive ones; and monads are not spatially or absolutely close to or distant from one another. [451] To say they are concentrated in a point or spread out in space is to use mental fictions, when we want to give free rein to our imaginations about things which can be grasped only by the intellect. Further, in this way of considering things, there is no extension or composition of the continuum, and all difficulties about points disappear. And this is what I wanted to say elsewhere, in my Theodicy, when I said that the difficulties about the composition of the continuum should suggest to us that things ought to be conceived in a very different way. Finally we need to see what must be superimposed [upon monads and their perceptions] if we add a substantial union, i.e. if we suppose that there is such a thing as corporeal and hence material substance; and whether it is then necessary to have recourse to mathematical body [i.e. infinitely divisible extended matter]. This will certainly not mean that monads literally have any absolute position, since in fact they are not the ingredients of matter, but only its requisites. So it will not on that account be necessary to postulate spatial indivisibles, which embroil us in so many difficulties. It is enough for corporeal substance to be something in virtue of which phenomena have extra-mental reality; but I would not want to suppose that it contained actual parts, except such as occur through actual division, nor indivisibles, except as limits.[n.13]
I think that monads always have full existence, and it is inconceivable that they should have the mere potential existence that parts are said to have in a whole. Nor do I see what a dominant monad could detract from the existence of other monads, since there is in fact no interaction between them, but only harmony. The unity of a horse’s corporeal substance does not arise from any ‘refraction’ of monads, but from an additional substantial vinculum which makes no change whatever in the monads themselves. A worm can be a part of my body and under my dominant monad, and can itself have other animalcules in its body under its dominant monad. But the domination and subordination of monads considered in the monads themselves consists only in degrees of perfection. . . .
It is true that whatever happens in the soul must be in harmony with whatever is happening outside the soul; but for this it is sufficient that what is happening in one soul should be internally coherent and correspond with whatever is happening in any other soul; nor is there any need to suppose anything apart from the totality of souls or monads; and according to this hypothesis, when we say Socrates is sitting, nothing other is meant than that [452] we and other relevant people have those appearances in virtue of which we have an intellectual awareness of Socrates and sitting.
Since you consider that the doctrine of transubstantiation can be reconciled with the hypothesis or supposition [fictio] of bodies reduced to phenomena, I would be grateful if you would tell me your opinion on this question. . . .
9. Leibniz to Des Bosses, 23rd August 1713
[481] . . . On more mature reflection, I have changed my mind on one point. I no longer think there is any absurdity in saying that the substantial vinculum, i.e. the very substance of a compound, is also ingenerable and incorruptible; for I think that in fact no corporeal substance should be admitted except where there is an organic body with its dominant monad, i.e. a living being, that is to say an animal [482] or something analogous to an animal; and I think that all other things are pure aggregates, or accidental rather than intrinsic unities. So since, as you know, I deny not only that the soul dies, but even that the animal [i.e. its body] dies, I will therefore say that neither does the substantial vinculum, i.e. the substance of the animated body, naturally come into being or die, but that since it is something absolute, it merely varies according to the changes the animal undergoes. Hence the corporeal substance or substantial vinculum of monads, though it naturally (i.e. in non-miraculous situations) requires monads, yet, since it is not in them in the way that a predicate is in its subject, it does not require them metaphysically, and hence it can be taken away or changed without affecting the monads, and can be accommodated to monads to which it does not naturally belong, so as to become their vinculum. Nor is any monad other than a dominant one ever naturally attached to a substantial vinculum, since the other monads are in a perpetual flux. I would not think of calling a substance the simultaneity of its parts, for otherwise it would be an aggregate. The parts which the vinculum belongs to, even if they are naturally connected to it, are not essential to it; so the parts can be removed naturally, gradually and in an orderly fashion, without affecting the absolute vinculum; but if it happens miraculously (all at once and discontinuously), the parts can be distinguished from the vinculum, and the vinculum itself be removed.
Now, although bread and wine are not living things, they are, like all bodies, aggregates of living things, and the substantial vincula of their individual living components constitute their substance. But the whole body of Christ has a [single] substantial vinculum, since it is a living body; so, if there is something which constitutes corporeal substance, it is there that you should seek the possibility of transubstantiation; but if there is no such thing, and bodies are mere phenomena, the substance of body will have to be sought in phenomena alone. But not in our phenomena, in which the previous images [species] remain, [n.14] but in those which appear to the Divine Mind and those [minds] to which God reveals them.[n.15] . . .
10. Leibniz to Des Bosses, 21st May 1714
[486] As for your assertion that the substantial vinculum is added to a compound already realised by modal vincula, I understand this as meaning that, leaving aside compound substances, monads comprise only accidental unities. But unless I am mistaken, such accidental unities will be mere phenomena. For since no mode can subsist by itself, but essentially presupposes a substantial subject, it follows that the vincula will have whatever reality they have in the modes of particular monads and the mutual harmony or sympathy of monads. I do not believe that you will accept that an accident can exist in two subjects at the same time. My opinion on relations is that David’s being a father is distinct from Solomon’s being a son; and the relation common to both is a purely mental thing based on the modes of individuals.
11. Leibniz to Des Bosses, 29th May 1716
[516] . . . But it is from the very reason of things (even without any reference to divine wisdom) that each of us judges that he is not the only existent, because there is no apparent reason why any one thing should be privileged [in this respect]. This is the only way you could convince someone who held that he alone existed, and that everyone else was only dreamed up by him. But there is a reason why those things that do exist should be privileged above things that do not exist, i.e. why not all possible things actually exist. But even if no creatures existed apart from the percipient, the orderliness of his perception would manifest the divine wisdom. So there is no circularity here, although even God’s wisdom can be known apriori, not simply from the orderliness of phenomena. For from the fact that there are contingents, it follows that there is a necessary being, understanding this in the way I showed in the Theodicy. If bodies were mere phenomena, it would not thereby follow that our senses were deceived. For the senses make no pronouncements about metaphysical questions. The veracity of the senses consists in the mutual harmony of phenomena, and our expectations are borne out by what actually happens if we reason properly on the basis of experience. . . .
[517] If bodies were mere phenomena, they would still exist as phenomena, like the rainbow.
You say bodies can be something other than phenomena, but without being substances. My opinion is that unless there are corporeal substances, bodies reduce to phenomena. Even aggregates are nothing but phenomena, since everything over and above the ingredient monads is added in perception alone, simply by their being perceived together. Besides, if monads were the only substances, it would be necessary either that bodies are mere phenomena, or that the continuum results from points, which is agreed to be absurd. Real continuity can only arise from a substantial vinculum. If nothing substantial existed apart from monads, i.e. if compounds were mere phenomena, extension itself would be nothing but a phenomenon resulting from co-ordinated simultaneous perceptions, and, in virtue of that very fact, all controversies about the composition of the continuum would come to an end. But that which is added to monads as the basis of the reality of phenomena is not a modification of monads, because it changes nothing in their perceptions. [n.16] For orders or relations, which join two monads, are in neither monad, but in both of them equally at the same time, that is, really in neither of them, but only in the mind. You will not understand this relation unless you add a real vinculum or something substantial, to be the subject of common or conjunctive predicates and modifications. For I do not think you are postulating an accident which would be in two subjects simultaneously, and have, so to speak, one foot in one subject and one in the other. . . .
[520] I once wondered what one of you Catholics should say if he wanted to abolish as superfluous all composite substance, that is anything in virtue of which phenomena could be said to be real. Given this, the substance of body itself would consist in [521] its constitutive phenomena — for example, the nature of whiteness consists in bubbles, like foam, or some similar texture, which is perceived by us only subconsciously. But the accident of whiteness consists in that conscious perception by means of which we are aware of whiteness. So, if God wanted to substitute blackness for whiteness without affecting the accidents of whiteness, he would bring it about that all percipients (for the truth of a phenomenon consists in the mutual agreement of percipients) retained the conscious perception of whiteness [n.17] and its effects, namely the perception of that which results from the constitutive [phenomenon]; but they would have a subconscious perception not of foam or little bumps (i.e. the texture which makes whiteness), but of troughs, or the texture which makes blackness. Thus all the conscious perceptions of bread would remain, but for the constitutive phenomena (which are still perceived by us, but subconsciously) would be substituted the universal perception of the constitutive or subconscious phenomena of flesh. . . .