Finally, these meditations furnish surprising consequences which are, nevertheless, of wonderful use in freeing men from doubts regarding the relation of God to created things, his fore- knowledge and fore-ordination and the union of the soul with the body, the origin of evil and other things of this nature. I say nothing here of the great applications that these principles have in the humanities, but at least I am able to say that nothing lifts our minds more to the knowledge and to the love of God, however much nature may help us in this. I confess that all these speculations are of no service without grace and that God gives grace to people who have never dreamed of these meditations, but God wishes also that we should not omit anything on our part and that each one of us according to his vocation and according to the time, should make use of the perfections which God has given to human nature. And since he has created us only that we may know and love him, we cannot work enough toward this nor can we make a better use of our time and of our energy except when we are occupied elsewhere for the public and for the welfare of others.

XVI: Arnauld to Leibniz

March 4th, 1687.

It has been a long time, M., since I received your letter, but I have been so busy since then that I have not been able to reply to it earlier.

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, nevertheless, 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 is 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 agreement 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 universe 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. You do 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 or efficient cause. There remains therefore only this "forethought of God," which can be the real and 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 understand 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 substantial form; therefore the essence of a body cannot 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 it was before.

3rd. That only animals have substantial forms, and that therefore in your opinion only animals are true substances.