I think furthermore that to attempt to limit true unity or substance to man alone is as shortsighted in metaphysics as it was in the realm of physics to desire to enclose the world in a sphere. And since true substances are so many expressions of the whole universe taken in a certain sense and so many reduplications of the divine work, it is in conformity with the grandeur and the beauty of the works of God, (seeing that these substances do not clash with one another,) to create in this universe as many of them as is possible and as superior reasons permit. The wholly bare supposition of extension destroys this wonderful variety, since mass, by itself (if we were able to conceive of it), is as much inferior to a substance which is perceptive and which represents the whole universe according to its point of view and according to the impressions or rather relations that its body receives mediately or immediately from all others, as a dead body is below an animal or as a machine is inferior to a man. It is, indeed, through the idea of substance that the evidences of the future are formed in advance and that the traces of the past are preserved forever in everything, and that cause and effect are exactly equivalent even to the slightest circumstance, although each effect depends upon an infinity of causes and every cause has an infinity of effects. It would not be possible to obtain this state of things, if the essence of the body consisted only in a certain form, motion or modification of extension, which was predetermined. Furthermore, there is nothing of the kind in nature; taken strictly, every thing is indefinite with regard to extension, and whatever we attribute to bodies are only phenomena and abstractions: this enables us to see how easy it is to fall into error if reflections so necessary for recognizing the true principles and for having a valid idea of the universe are not made. It seems to me that as much prejudice is displayed in refusing to accept so reasonable an idea as this, as there would be in not recognizing the grandeur of the world, the subdivision to infinity and the mechanical explanations of nature. It is as great an error to conceive of extension as a primitive concept without looking into the real concept of substance and of action, as it was formerly to be contented with considering substantial forms as a whole without entering into details as to the modifications of extension.

The great number of souls (to which, however, I do not necessarily attribute in every case pain and pleasure), should not trouble us any more than do the great number of the atoms put forward by Gassendi, which are quite as indestructible as the soul. On the contrary it is one of the perfections of nature to have so many of them, since a soul or indeed a living substance is infinitely more perfect than an atom, which is without variety or subdivision. Every living thing contains a world of diversity in a real unity. Our experience is in favor of this great number of living things; we find that there is a prodigious quantity of them in a drop of water tinctured with powder and with one blow millions of them can be killed so that neither the frogs of the Egyptians nor the quails of the Israelites of which you spoke, M., at all approach the number. Now, if these animals have souls, the same must be said of their souls which can probably be said of the animals themselves; namely, that they have been living from the very creation of the world and that they will live to its end, and that birth being apparently only a change consisting in growth, so death is only a change or diminution which causes this animal to re-enter into the engulfing of a world of minute creatures, where perceptions are very limited until the command comes calling them to return to the theater of action. The ancients made the mistake of introducing the transmigration of souls, in place of the transformation of the same animal which always preserves the same soul. They put metempsychoses in place of metaschematismi. Spirits, however, are not subjected to these revolutions, or rather these revolutions of bodies must serve the divine economy for the sake of spirits. God creates them when it is time and he detaches them from the body, at least from the material body by death; since they must always preserve their moral qualities and their memory in order to be perpetual citizens of that universal republic, absolutely perfect, whose monarch is God. This republic can never lose any of its members and its laws are superior to those of the body. I grant that bodies by themselves without the soul have only a unity of aggregation, but the reality which inheres in them comes from the parts which compose them and which retain their substantial unity through the living bodies that are included in them without number.

Nevertheless, although it is possible that a soul have a body made up of animated parts or of separate souls, the soul or the form of the whole is not, therefore, composed of souls or forms of parts. In regard to an insect which is cut in two, it is not necessary that the two parts shall remain animated, although there may be some movement in them, at least the soul of the whole insect will remain only on one side and as in the formation and in the growth of the insect the soul has already been in a certain part alive from the very start, it will remain also after the destruction of the insect, still alive in a certain part, which will always be as small as is necessary to serve as an asylum from the action of him who is tearing or destroying the body of this insect. We need not, however, imagine with the Jews that there is a little bone of irrefrangible hardness where the soul preserves itself.