(2). I do not see that your substantial forms can remedy this difficulty, for the attribute of the ens which is called unum, taken as you take it, strictly metaphysically, must be essential and intrinsic to what is called the unum ens. Therefore, if a particle of matter is not a unum ens but plura entia, I do not see how a substantial form, which being really distinguished from it, could only give it an extrinsic property- how this substantial form could make it cease being a plura entia and should make it a unum ens by an intrinsic property. I understand easily that this would give us a reason for calling it

unum ens, if we did not take the word unum in this metaphysical strictness. Substantial forms, however, are not called for in order to be able to give the name one to an infinity of inanimate bodies, because, is it not correct usage to say that the sun is one, that the earth which we inhabit is one, etc? It is not evident, therefore, that there is any necessity for admitting these substantial forms in order to give to bodies a true unity, which they would not otherwise have.

(3). You admit these substantial forms only in animate bodies. *004 Now there are no animate bodies which are not organized, nor are there any organized bodies which are not plura entia; therefore your substantial forms, far from preventing bodies to which they are joined from being plura entia, must themselves become plura entia in order that they may be joined.

(4). I have no clear idea of these substantial forms or souls as applied to brutes. It must be that you regard them as substances, since you call them substantial, and since you say that only substances are truly real beings, among which you include above all these substantial forms. Now I know only two sorts of substances, bodies and minds, and it is for those who claim that there are others to show me them, according to the maxim with which you conclude your letter, "that nothing should be considered certain without a basis." Suppose therefore that these substantial forms are either bodily or mental; if they are bodily they must be extended and consequently divisible and divisible to infinity; hence it follows that they are not a unum ens but

plura entia; just as are the physical bodies which they animate; they are not therefore able to impart a true unity. If however, the substantial forms are mental, their essence will be to think, for this is what I understand by the word mind. It is hard for me to understand how an oyster thinks or a worm thinks; and since you say in your last letter that you are not sure but that plants have a soul, have a life or a substantial form, it must be you are not sure that plants do not think, because their substantial forms, if they have any, not being corporeal because they are not extended, must be mental, that is to say, a substance which thinks.

(5). The indestructibility of these substantial forms or souls in brutes appears to me still more untenable. I asked you what became of the souls of these brutes when they died or when they were killed, just as when worms were burned what became of their souls. You reply "that they remain for each worm in a small part of the body that remains alive. This will always be as small as is necessary to serve as a shelter from the action of the fire which tears to pieces or which destroys the bodies of these worms." This brings you to say that "the ancients were mistaken in introducing the transmigration of souls in place of the transformation of the same animal which always preserves the same soul." Nothing can be imagined more subtle for meeting the difficulty that I raised, but you will have to be on your guard, M., against what I am about to say; when a silk moth casts its eggs each one of these eggs in your opinion has the soul of a silk worm, whence it happens that five or six months later little silk worms hatch out. Now, if a hundred of these silk worms had been burned there would be, in your opinion, a hundred souls of silk worms in so many little particles of the ashes; but on the one hand I do not know any one whom you can persuade that each silk worm after having been burned remains the same animal preserving the same soul joined now to a speck of ashes which was formerly a little portion of its own body; and, on the other hand, if this were so, why is no silk worm born out of these specks of ashes as they are born out of the eggs?

(6). This difficulty appears greater in the case of animals, where it is known certainly that they cannot be born except through the alliance of two sexes; I ask, for example, what became of the soul of the ram which Abraham offered in place of Isaac and which he burned? You will not say that it passed into the foetus of another ram, for this would be the metempsychosis which you condemn; but you reply that it remained in a particle of the body of this ram reduced to ashes and that therefore it is only the transformation of the same animal which has always preserved the same soul. This could be said with some appearance of truth in your hypothesis of the substantial forms of a caterpillar which becomes a butterfly, because the butterfly is an organized body quite as much as is the caterpillar, and therefore it is an animal which can be considered the same as the caterpillar because it preserves many of the parts of the caterpillar without any change, and the other parts have changed only the forms. But this part of the ram, reduced to ashes, in which the soul of the ram has taken refuge, not being organized, cannot be taken for an animal, and therefore the soul of the ram which is joined to it, does not compose an animal, much less a ram, such as the soul of a ram should. What will then become of the soul of this ram in this cinder? For it cannot separate itself away, to go elsewhere, since this would be a transmigration of the soul, that you have condemned. The same is the case with an infinity of other souls which would never form animals because of being joined to particles of matter not organized, but which invisible could become organized according to laws established in nature. What an infinity of monstrous things would be this infinity of souls joined to bodies which cannot become animated!

Not long since I saw what Abbe Catelan replied to your answer in The News of the Republic of Letters for the month of June. What he said there seemed very clear to me, perhaps however, he did not entirely understand your thought; therefore, I am awaiting the reply which you will make to him. I am, Monsieur,

Your very humble and very obedient servant,

A. A.

XXI: A. Arnauld to Count Ernst von Hessen-Rheinfels

August 31st, 1687.