I do not understand very well what you mean by this ‘‘distincter expression which our soul bears of that which is now happening to its body,’’ and how it comes about that when someone pricks my finger my soul knows of this pricking before it feels the pain of it.. This very “‘distincter expression,’’ etc., ought to let it know therefore an infinity of other things which happen in my body which, never- theless, it does not know, for instance all that goes on in the process of digestion and of nutrition.
As for your saying that although my arm raises itself when I wish to raise it, it is not because my soul causes this movement in my arm but it its LEIBNIZ. ARNAULD. HESSEN-RHEINS ELS. 173 because ‘‘when I wish to raise it it is exactly at the very moment when everything is ready in the body for this very effect, in such a way that the body moves itself by virtue of its own laws, although it happens through the wonderful but unfailing agree- ment of things among themselves that these laws conspire together at the very same moment that the will makes its resolution. For God had regard to this in advance when he resolved upon this sequence of all the things in the universe.’’ It seems to me that this is to say the same thing in other terms that those say who maintain that my will is the occasional cause for the movement of my arm and that God is its real cause; for they do not claim that God does this at the moment by a new act of will each time that I wish to raise my arm, but by a single act of the eternal will by which he has chosen to do everything which he has foreseen that it will be necessary to do, in order that the unt- verse might be such as he has decided it ought to be. Does not what you say come to this very thing, namely that the cause of the movement of my arm when I wish to lift it is “‘the wonderful but unfailing agreement of things among themselves which results because God had them in mind in advance when he resolved upon this sequence of all the things in the universe’? For this forethought of God has not been able to bring about any event without a real cause. -We must, therefore, find the real cause of this movement of my arm. Youdo not wish it to be my will. I do not think, either, that you believe a body can move itself or any other body as a real orefficient cause. There remains therefore only this ‘forethought of God,’’ which can be the real.and 174 CORRESPONDENCE.
efficient cause of the movement of my arm. Now you, yourself, called this forethought of God his resolve; and resolve and will are the same thing. Therefore, according to you, every time that I wish to raise my arm, it is the will of God which is the real and efficient cause of this movement.
In regard to the second difficulty, I now under- stand your position to be very different from what I thought, for I supposed that you would reason thus: the body should be the true substance; now there can be no true substances which have no true unity nor can there be any true unity which has not a sub- stantial form; therefore the essence of a body can- not be its extension, but every body besides its extension should have a substantial form. To this I have replied that a divisible substantial form, such as almost all those who hold to substantial forms understand them, could not give to a body any unity that it did not have without this substantial form.
You agree, but you claim that every substantial form is indivisible, indestructible and ingenerable, being produced only by a real creation; whence it follows: 1st. That every body which can be divided so that each part will remain of the same nature as the whole, such as metals, stones, wood, air, water and the other fluid bodies, have no substantial form.
2nd. That the plants have none, either, since a part of a tree, whether placed in the ground or grafted to another tree, remains a tree of the same sort that tt was before.
3rd. That only animals have substantial forms, and that therefore in your opinion only animals are true substances.
LEIBNIZ. ARNAULD. HESSEN-RHEINFELS. t75 4th. And since, as you say, you are not very sure whether brutes have souls or substantial forms, it follows that with the exception of man there is nothing substantial in the visible world, because you claim that substantial unity requires a complete being, indivisible, and through natural means inde- structible. This can be found only ina soul or a substantial form like that which I call the Me.
All of this means that every body whose parts are only mechanically united 1s not a substance but only a machine or an aggregate of several sub- stances.
I will begin with this last. And I will say frankly that it is only a dispute regarding a word. For St. Augustine did not hesitate to recognize that bodies have no real unity; because a unit should be indivisible and no body is indivisible. There is, therefore, no true unity excepting in Spirit, any more than there is a true Me outside of them. Now, what 1s your conclusion from that? ‘‘That there is nothing substantial in those bodies which have no soul or substantial form.’’ In order that this conclusion may be valid we must first of all define substance and substantial in these terms, ‘“‘I call substance and substantial that which has a true unity.’’ But since this definition has not yet been received there is no philosopher who has not as much right to say, “I call substance that which is not modality or manner of being,’’ and he could therefore maintain that it is untrue to say that there is nothing substantial in a block of marble, “‘because this block of marble is by no means a manner of being of another substance, and all that can be said of it is that it is not a single 176 CORRESPONDENCE.
176 CORRESPONDENCE.
substance but several substances joined together mechanically.’’ This philosopher would say ‘“‘this is what seems to me paradoxical: that there should be nothing substantial in that which seems to be made up of several substances.’’ He could add that he understood still less what you meant by the words ‘‘bodies would be without doubt something imaginary and only of appearance if they were com- posed only of matter and its modifications.’’ For you postulate only matter and its modifications in everything that has no soul or no substantial, inde- structible, indivisible and ingenerable form and it is only in the case of animals that you admit this class of forms. You will therefore be obliged to say that all the rest of nature is something imaginary and merely an appearance, and for a still stronger reason. you would have to say the same thing of. all the works of men.
I cannot agree to these latter propositions, but I see no objection to thinking that in every corporeal nature there is only a machine and an aggregate of substances, because of no one of its parts could one say strictly that it is a single substance. This serves merely to make evident what is worth while noticing, as St. Augustine has done, that the substance which thinks, or a spiritual substance, is through this fact much more excellent than extended or corporeal substance. The spiritual substance alone has a true unity and a true ego, while the corporeal substance does not have them. It follows from this, that this fact, that the body has no true unity when its essence is extension, cannot be put forward to prove that extension is not of the essence of the body; for, perhaps, the essence of LEIBNIZ. ARNAULD. HESSEN-RHEINFELS. oe rf the body has no true unity, as you grant in the case of all those which are not united to asoul ortoa substantial form.
I do not know, M., what inclined you to believe that brutes have these souls or substantial forms, which, according to you, must be indivisible, inde- structible and ingenerable. It is not because you consider it necessary to explain their actions, for you say expressly “‘that all the phenomena can be explained mechanically or by the corpuscular philosophy in accordance with certain postulated mechanical principles, without going into’the ques- tion whether there are souls or not.’’ It is also not because the bodies of brutes need to have a true unity and because they are not mere machines or aggregations of substances; if plants are merely the latter what necessity is there that brutes should be anything else? Further, it is not clear how this opinion can be easily maintained, if we consider these souls as indivisible and indestructible. What would be said of a worm, of which, when cut in two, both parts move off as before? Ifa house where a hundred thousand silk-worms were being kept should catch fire and burn up, what would become of those one hundred thousand indestructible souls? Would they exist apart from all matter like our souls? In the same way, what became of the souls of those millions of frogs which Moses caused to die when he stopped the plague? And of that innumerable number of quails which the Israelites killed in the desert or of all the animals which perished in the flood? There are also other embar- rassing questions in regard to the condition of these souls in each brute at the moment that they are con- 178 CORRESPONDENCE ceived. Is it that they are tn semtnibus? Are they there indivisible and indestructible? Quad ergo fit, cum irrita cadunt sine ullis conceptibus semina? Quid cum bruta mascula ad foeminas non accedunt toto vitae suae tempore? It will suffice to have indicated these difficulties.
There still remains the discussion of the unity which a reasoning soul has. It is agreed that it has a true and a perfect unity, a true Me, and that it communicates in some sort this unity and this Me to that composite whole of the soul and body which is ealled the man; for, although this whole ts not indestructible because it perishes when the soul is separated from the body, it is indivisible in this sense, that half a man cannot be conceived of. In considering the body apart, however, in the same way that our soul does not communicate to it its indestructibility, we cannot see, properly speaking, that it communicates either its true unity or its indivisibility. Even though it be united to our soul, nevertheless, its parts are truly united among themselves only mechanically, and thus there is not a single bodily substance, but an aggregation of many corporeal substances. Not less true is it that it is quite as divisible as all the other bodies in nature. The divisibility, however, is inconsistent with unity, therefore it has no true unity. But you say, it acquires the unity through the soul, that is to say, because it belongs to a soul which ts a true unit; this, however, is not an intrinsic unity in the body, but is like that of different provinces which are governed bya single king and thus constitute one kingdom.
Although, however, it is true that there is no real LEIBNIZ. ARNAULD. HESSEN-RHEINFELS. 179 unity except in intelligent natures, each of which can say the word Je, there are, nevertheless, differ- ent degrees in this inexact unity which belongs to bodies; for although there are no bodies which are not made up of several substances there is, never- theless, reason for attributing more unity to those whose parts work together for a similar purpose like a house or a watch than to those whose parts are only in contact one with another like a pile of stones or a bag of coins and only these latter can properly be called an accidental aggregation. Almost all natural bodies, which we call one, like a piece of gold, a star, a planet, are of the first kind; but there are none which appear to be more so than the organized bodies, that is, the animals and plants; though there is no reason to assign souls to them on this account (and I] think also that you assigned none to plants). For why should not a horse or an orange be consid- ered each one as a complete and whole work quite as well asachurch orawatch? What is essential in order that a thing may be called one (that is, this oneness which applies to bodies, but which is very different from that that applies to spiritual natures) when the parts are united among themselves only mechanically as are the parts of the machine? Is it not the greatest perfection that they can have, that they are machines so wonderful that only an all-powerful God could have constructed them? Our body, considered by itself, is therefore ene in this sense. The relationship, which an intelligent nature, united to it and governing it, has with it, may, perhaps, add some unity, but it is not that kind of unity which pertains to spiritual natures.
I confess, M., that my ideas on the laws of motion 180 CORRESPONDENCE.
are not clear and distinct enough to enable me to pass judgment upon the difficulty which you have brought up against the Cartesians. The one who replied to you is the Abbé Catelan who has a good mind and is a good geometer; since I left Paris I have not had much intercourse with the philoso- phers of that country. Inasmuch, however, as you -have decided to reply to this Abbé, and as he will perhaps wish to defend his position, it is to be hoped that these discussions will so clear up the difficulty that it will be possible to know which side to take.
I thank you very much for the desire you show to know how I am. I am thankful to say that I am very well for my age, only I had a very bad cold at the beginning of the winter. I am very glad that you are thinking of completing your arithmetical machine. It would be a pity if so fine an invention were lost. I desire greatly, however, that the inten- tion in regard to which you wrote a word to the Prince, who has so much affection for you, may not remain without its effects, for there is nothing towards which a wise man should work with more care and with less of delay than towards what has to do with his salvation. I am, Monsieur, Your very humble and obedient servant. A. ARNAULD.
XVII Letbniz to Arnauld.
Géttingen, April 30, 1687. Monsieur:: Since I regard your letters as personal benefactions to me and as sincere marks of your liberality, I LEIBNIZ. ARNAULD. HESSEN-RHEINFELS. 181 have no right to ask for them and consequently your reply is never too late. However agreeable and useful they may be to me, I take into con- sideration what you owe to the public weal and thus suppress my desires. Your criticisms are always instructive and I will take the liberty to go through them in order.
Ido not think that there is any difficulty in my saying that ‘“‘the soul expresses more distinctly, other things being equal, that which pertains to its own body’’; since it expresses the whole universe in a certain sense according to the special relation of other bodies to itself, it is not able to express all things equally, otherwise there would be no distinc- tion between souls, but it does not follow from this that the soul should perceive perfectly whatever goes on inthe parts of its body, since there are degrees of relationship between these parts them- ‘selves and these parts are no more equally expressed ‘than are external things. The greater distance of the latter is made up for by the smallness or by some other hindrance in the internal parts. Thales saw the stars though he did-not see the ditch which was at his feet.: The nerves and membranes are for us the parts which are more sensitive than the others and it is, per- haps, only through them that we perceive what seems to happen to the others, because the movements of the nerves, or of the liquids in them, imitate the impressions better and confuse them less, and the most distinct expressions of the soul correspond to the most distinct impressions of the body. Meta- physically speaking, it is not the nerves which act upon the soul, but the one represents the.state of the 182 CORRESPONDENCE.
other through the spontaneous relation; it must also be remembered that too many things take place within our bodies to be all separately perceived; we feel only a certain result, to which we are accus- tomed, and we are not able to distinguish the ele- ments that are involved, because of their multitude. Just as when we hear from afar the sound of the sea, we do not distinguish what each wave does, although each wave has its effect upon our ears. When a striking change happens in our body, we notice it at once and more clearly than the changes outside, which are not accompanied by any special change in our organs.
Ido not say that the soul knows the pricking before it has the sense of pain, except as it knows or expresses confusedly all things in accordance with the principles already established. This expres- sion, however, although obscure and confused, which the soul has in advance of the future, is the real cause of that which happens to it and of the clearer conception which it will have later when the obscurity shall have worked out. The future state is only a consequence of the preceding.
I said that God created the universe in such a way that the soul and the body, each acting according to its laws, agree in their phenomena. You think, M., that this coincides with the hypothesis of occasional causes. Were this so I should not be sorry, and I am always glad to find those who hold my positions. I see, however, the reason for your thinking this. You are of the opinion that I would not say a body can move itself, and, the soul not being the real cause either of the motion of the arm or of the body, there- fore the cause must be God. My opinion, how- LEIBNIZ. ARNAULD. HESSEN-RHEINFELS. 183 ever, is different. I hold that whatever reality there is in the state which is called motion, may issue quite as well from the bodily substance as the thought and will proceed from the spirit. Every- thing happens to each substance in consequence of the first state which God gave to it in creating it, and putting aside extraordinary interventions the ordinary agreement consists only in the conserva- tion of the substance itself conformably to its pre- ceding state and to the changes which it carries in itself. Nevertheless, we have the right to say that one body pushes another; that is to say, that one body never begins to have a certain tendency except- ing when another which touches it loses proportion- ately, according to the constant laws which we observe in phenomena; and since movements are rather real phenomena than beings, a movement as a phenom- enon is in my mind the immediate consequence or effect of another phenomenon, and the same ts true in the minds of others The condition of one sub- stance, however, is not the immediate consequence of the condition of another particular substance.
I dare not maintain that plants have no souls, nor life, nor any substantial form; since, although one part of a tree planted or grafted can produce a tree of the same kind, it is possible that there is in ita seminal part which already contains a new plant, as it is likely there are living animalcula although very small in the seed of animals which can be transformed into a similar animal; I do not there- fore dare to maintain that animals alone are living and endowed with substantial forms. Perhaps there is an infinity of degrees in the forms of corporeal substances.
184 CORRESPONDENCE.
You say, M., that ‘‘those who hold to the hypoth- esis of occasional causes, saying that my will is the occasional cause, while God is the real cause of the movement of my arm, do not claim that God does this at the moment by a new volition, which he has each time I wish to lift my arm, but through that single act of eternal will, by which he resolved to do everything which he foresaw would be neces- sary for him to do.’’ Tothis I reply that we can say with the same reasoning, that miracles also are not the result of a new act of will on God’s part, being conformable to a general plan; and I have already stated, in what precedes, that every act of will on God’s part involves all the others, but with a certain order of priority; if I properly understand the position of the authors of occasional causes, they introduce a miracle which is not less miraculous for being continual, for it seems to me that infre- quency does not constitute the conception of mir- acle. It will be said that God acts in that, only according to a general rule and consequently with- out miracle, but Ido not grant this consequence and- I think that God could mz*e general rules with regard to the miracles themselves. For instance, if God resolved to give his grace immediately, or to perform some other action of this nature every time that. a certain condition came about. this action would, nevertheless, be a miracle although quite in the ordinary. I confess that the authors of occasional causes can give another definition of the term, but it seems that according to usage a miracle differs internally and substantially from that which results from ordinary activity, and its distinctiveness does not depend upon its unusualness; properly LEIBNIZ. ARNAULD. HESSEN-RHEINFELS, 185 speaking, God performs a miracle when he does any- thing which surpasses the powers which he has given to created things and which he maintains in them; for example, if God should make a body, which was put in circular motion by means of a sling, to go on freely in a circular line even when it was released from the attachment, this, when it was neither pushed nor retained by anything, would be a mir- acle, for, according to the laws of Nature the body shouid travel along the line of the tangent: if, more- over, God should decide that such should always be the case, he would perform a natural miracle, for this movement could not be explained by anything more simple. In the same way, we should have to say in accordance with the current conception, that if the continuation of the motion were beyond the power of bodies, the continuation of the motion would be atrue miracle; while my position is that the corporeal substance has the power to continue its changes according to the laws which God has put into its nature and which he maintains there. To make myself better understood I will add that the activities of the mind change nothing at all in the nature of the body, nor the body in that of the mind; and I will also add that neither does God change anything on the occasion of their action except when he performs a miracle. In my opin- ion, things are so concerted together that the mind never desires anything efficaciously excepting when the body is ready to accomplish it in virtue of its own laws and forces; while, according to the authors. of occasional causes, God changes the laws of the ‘yody on the occasion of the action of the soul and, vice versa, hat is the essential difference between our 186 CORRESPONDENCE.
positions. Therefore, we should not ask how the soul can give any motien or new determination to the animal spirits, since it never does anything of the kind, for there is no interaction between spirit and body, and there is nothing which can determine what degree of velocity a mind will give to a body, nor what degree of velocity God may be minded to give to the body on the occasion of the mind’s action according toa certain law. The same difficulty ts found with regard to the hypothesis of occasional causes which there is in the hypothesis of a real influence of the soul upon the body and wice versa; because we can see no relation or basis for such a rule. If one were to say, as M. Descartes seems to, that the soul, or God on the occasion of its acting, changes merely the direction or determination of the motion and not the force which is in bodies, (since it does not seem probable to him that God would interrupt at each moment on the occasion of the willing of spirits, this general law of nature, namely, that the same force should perdure), I would reply that it will be quite difficult to explain what connection there can be between the thoughts of the soul and the sides or the angles of direc- tion of bodies, and furthermore that there is in nature another general law which M. Descartes has not perceived but which is, nevertheless, important —namely, that the sum total of the determinations or directions must always perdure. For I find that if any straight line be drawn, for example, from east to west, through a given point, and if all the direc- tions of all the bodies in the world in so far as they advance toward or move away in lines parallel to this line be calculated, the difference between the LEIBNIZ. ARNAULD. HESSEN-RHEINFELS. 187 sums of the quantities of all the easterly direc- tions and of all the westerly directions will ever be found the same, whether certain particular bodies which might alone be supposed to have relations among themselves, be regarded or whether the whole universe be regarded. In this latter case the difference is always zero. Everything is per- fectly balanced and the easterly and westerly direc- tions in the universe are exactly equal. If God wished to do anything against this principle it would be a miracle.
It is therefore much more reasonable and more worthy of God to suppose that he has created the machinery of the world in such a fashion from the very start, that without doing violence at every moment to the two great laws of nature, that of force and that of direction, but rather by following them exactly, (except in the case of miracles,) it so comes about that the internal springs of bodies are ready to act of themselves, as they should, at the very moment when the soul has a conforming desire or thought. The soul, in turn, has had this desire or thought only conformably to preceding states of the body and thus the union of the soul with the machinery of the body and with the parts which compose it, and the action of the one upon the other consists only in this concomitance, which betokens the wonderful wisdom of the Creator much more than any other hypothesis. It cannot be denied that this at least is possible, and that God is a sufficiently great workman to be able to carry it out; therefore, it can easily be decided that this hypothesis is the most probable, being the simplest and most intelligible and at once avoiding all diffi- 188 CORRESPONDENCE, culties; for example, the difficulties involved in criminal actions, where it seems much more reason- able to let God intervene only through the conserva- tion of the created forces.