I should like to be able to explain as clearly and decisively the other question with regard to the substantial forms. The first difficulty which you point out, M., is that our souls and our bodies are two substances really distinct; therefore, it seems that one is not the substantial form of the other. I reply that in my opinion our body by itself, leaving out of question the soul, the physical body, can be called one substance only by a misuse of terms, just as a machine or a pile of stones might be called one although they are beings only by accumulation. The regular or irregular arrangement does not constitute a substantial unity. Aside from this, the last Lateran council declares that the soul is veritably the substantial form of our body.

Regarding the second difficulty I agree that the substantial form of our body is indivisible and this seems also to be the opinion of St. Thomas. I agree, also, that every substantial form, or, indeed, every substance is indestructible and also ingenerable, which latter was also the opinion of Albertus Magnus and among the ancients of the author of the book called De diaeta, usually attributed to Hippocrates. They can come into being therefore only by an act of creation. I am a good deal inclined to believe that all the births of unreasoning animals, which do not deserve a new act of creation, are only transformations of another animal already living, but at times invisible. Consider for example, the changes which happen to a silk-worm and other like creatures, where nature has disclosed its secrets in certain instances while it conceals them in others. Thus, brute souls would have all been created from the very beginning of the world, in accordance with that fertility of seeds mentioned in Genesis, but the reasoning soul is created only at the time of the formation of its body, being entirely different from the others souls which we know because it is capable of reflection and imitates on a small scale the divine nature.

Thirdly, I think that a block of marble is, perhaps, only a mass of stones and thus cannot be taken as a single substance but as an assembly of many. For, supposing there are two stones, (for example, the diamond of the Grand Duke and that of the Great Mogul), the same collective name could be put for both of them, and we could say that it is a pair of diamonds, although they are very far apart; but, we should not say that these two diamonds compose one substance. Matters of greater or less in this case would make no difference. They might be brought nearer together, even to touching. Yet they would not be substantially one, and if, after they had touched they were joined together by some other body, constructed to prevent their separation- for instance, if they were set in the same ring- all this would make only what is called a unity by accident, for it is as by accident that they are subjected to the same motion. I hold, therefore, that a block of marble is no more a thoroughly single substance than would be the water in a pond with all the fish included, even when all the water and all the fish were frozen; or any more than a flock of sheep, even when the sheep were tied together so that they could only walk in step and so that one could not be touched without producing a cry from all. There is as much difference between a substance and such a being, as there is between a man and a community- say a people, an army, a society or college, which are moral beings, yet they have an imaginary something and depend upon the fiction of our minds. Substantial unity calls for a thoroughly indivisible being, naturally indestructible since its concept involves all that must happen to it. This characteristic cannot be found either in forms or in motions, both of which involve something imaginary as I could demonstrate. It can be found, however, in a soul or a substantial form, such as is the one called the me. These latter are the only thoroughly real beings as the ancients recognized and, above all, Plato, who showed very clearly that matter alone does not suffice for forming a substance. Now, the me above mentioned or whatever corresponds to it, in each individual substance can neither be made nor destroyed by the bringing together or the separation of the parts. Such juxtapositions are wholly apart from the constitution of a substance. I cannot tell exactly whether there are other true corporeal substances beside those which have life. But souls serve to give us a certain knowledge of others at least by analogy.

All this can contribute to clear up the fourth difficulty, for, without bothering with what the Schoolmen have called

formam corporeitatis, I assign substantial forms to all corporeal substances that are more than mechanically united.