Disputationes metaphysicae

1. Although universal unity in some way differs from formal unity, as we have said, nevertheless, because it is not a unity according to the thing but according to reason, the principle of each unity is not diverse in the thing; and therefore it is not necessary to raise diverse questions about them; but, the principle of formal unity being explained, that of the universal will have been explained, because the latter is not founded in things except by means of formal unity. And therefore Ferrariensis rightly said, Contra Gentiles II, c. 95, that when it is asked from what genus and difference are taken, it is not asked about genus and difference in second intention, that is, as through reason they have unity or a relation of reason, but in first intention, that is, according to the formal unity or agreement which they can have in the thing. But the discussion here is of the physical principle; for just as above, individual unity having been explained, we inquired into and explained its principle, that is, the physical foundation which it can have in the thing, so here we investigate a similar principle with respect to formal unity, which is either the unity of the genus or of the difference, or of the species composed of both; for I now omit transcendental formal unity, because either it is analogous, and so is not unity simply, or, if it is univocal, it is to be reduced to the generic, as I said above, and it has the same proportional foundation, as I shall explain.

2. The question so declared, then, coincides with that common one, whence genus and difference are taken. And the reason for doubting is that it is commonly wont to be said that the genus is taken from matter and the difference from form; which nevertheless does not appear true. First, because also in the angels the formal unity of genus and species is found; and yet in them neither matter nor form is found. Secondly, because if the genus were taken from matter, then things which did not have common matter could not have a common genus either; the consequent is openly false, because both material substances agree with immaterial ones in some genus, and terrestrial bodies with celestial ones, although they do not agree in matter. Thirdly, because even in substances having similar matter the genera are not taken from matter, as is evident of the genus of living thing, animal and the like; for the living thing does not have life from matter but from form; and so of the others. On the contrary is the fact that that manner of speaking is that of almost all the ancients, but especially of St. Thomas, De ente et essentia, cc. 4, 5 and 6; Contra Gentiles II, c. 95; and the question De spiritualibus creaturis, a. 1; and Averroes indicates it, Metaphysics X, at the end, comm. 26, on account of Aristotle saying there that the corruptible and the incorruptible differ in genus, because they also differ in matter. In which he indicates that the genus either is matter or is altogether to be taken from matter.

The former opinion is rejected

3. In this matter there can be a twofold mode of speaking. The former is that matter and form, properly and rigorously taken, are the proper and necessary principles of generic or specific formal unity; and in this sense that the genus is taken from physical matter as from its proper principle, but the difference or species (for these two are reckoned the same, since the difference constitutes the species) from the form. And in this manner those seem to have thought who deny that immaterial things are composed of genus and difference, but only things composed of matter and form; among whom is Durandus, In II, dist. 3, q. 1; and Albert indicates it, on the Categories, chapter on Substance; and Giles in the same place, and Quodlibet I, q. 8; for, moved (as it seems) by this reason, they deny that corporeal substances are univocally substances with incorporeal ones. Which Averroes too denied, in the place cited above, of terrestrial and celestial bodies, because he thought that the heavens do not consist of matter, of which elsewhere. It is true that it does not necessarily follow from this principle that these authors denied genera and differences in the angels or the heavens, because they could have thought that they have a generic agreement among themselves, even if they denied that they have it with inferior substances. Nevertheless, if they think so, they will be able to bring forward no probable reason on account of which they deny common genera to these substances composed of matter and form and to those immaterial ones which admit in themselves the composition of genus and difference; because, just as in this they are similar to inferior substances, so they can have with them some union and generic agreement; nor will this be repugnant to their simplicity or perfection; they will speak more consistently, therefore, by saying that, by the very fact that they do not have matter and form, they cannot have genus and difference either, because these are founded in them. But of this assertion so expounded I do not see what foundation can be brought forward, except that, just as matter is in potency to several forms and with them composes diverse essences, so the genus is related to several differences. But this opinion so expounded is openly false, as the arguments made at the beginning and those which we shall bring forward convince; and that foundation is very light, because that agreement is not through true likeness and propriety, but only according to a certain proportion.

Resolution of the question

4. How the genus is said to be taken from matter, the difference from form.—The second opinion, then, is that matter and form, not according to physical propriety but according to a certain proportion and analogy, are the principles from which genus and difference are taken. For matter is the first and as it were essential or substantial potency of the substantial nature, of itself indifferent to several natures or acts; but form is the first substantial act determining or constituting the nature. Because, then, the genus is something potential and indifferent, and is actuated and determined by the difference to a certain grade or species of nature, therefore the genus is said to be taken from matter and the difference from form, that is, through a certain proportion to matter and form. And this is the opinion of Aristotle, Metaphysics VIII, text 6; of St. Thomas, in the said opusculum De ente et essentia, and Contra Gentiles II, c. 95, and In Metaph. VII, lects. 11 and 12, and in other places to be cited below. And this sense is true and easy. It must be said, then, speaking universally, that the principle of formal unity is the whole essence and nature of the thing, yet in a diverse way; for the principle of generic unity is the nature itself, as it is further perfectible or determinable, or as it has agreement and likeness with others in some potential grade, or one further determinable. But of specific unity, or of the difference, it is the same nature according to its ultimate essential perfection. It is proved, first, by the reasons given, because no other mode can be assigned which is common to all substances and accidents and forms. Secondly, because in material substances themselves neither the form nor the matter is a sufficient principle of genus and difference; because, as was said above, both genus and difference in some way express the whole nature of the thing, and therefore can be predicated of the species. Whence, if per impossibile we understood a composite of the rational soul and another matter of another notion from that of which man now consists, from such matter and form the genus and difference by which man now essentially consists would not be taken; because rational, although it is taken chiefly from the soul, nevertheless essentially includes such matter. And conversely, although this matter is feigned without composition with any form, no proper genus of substance could be taken from it, except perhaps the genus of matter, with respect to which matter itself is related as the whole nature, from which, as it has agreement with the matter of the heaven in some further determinable grade, such an incomplete genus can be taken; and consequently from the same, as it has completion in its essence, will be taken the ultimate difference constituting the species of such matter; and the same holds in its own way in the form; therefore in each thing every unity of this kind is taken from the whole nature, compared or conceived in one way and another. But this is to be understood with due proportion, for in complete and integral substances it is true simply and with all propriety, because they are those which have proper and integral natures; but because in partial substances too, such as are matter and form, generic and specific unity is found in its own way, in them it must be understood with proportion that genus and difference of this kind are taken from the whole nature, namely partial, that is, from the whole entity of the form or the matter, according to diverse notions; which is to be accommodated in the same way to accidental forms too, as can be seen at length in St. Thomas, opusc. De ente et essentia, c. 7.

Answers to the arguments

5. In the angels genera and differences are truly found.—To the first, then, we confess that in the angels there are genera and species, as St. Thomas declares at length in the said opusculum De ente et essentia, cc. 5 and 6, and I, q. 50, a. 2, ad 1, and others, as we shall treat below in disputing about the intelligences. Nor is it necessary that there be matter and form in them, because, as we have said, these are not always the principles of genus and difference, but any nature, even simple, provided it is such that it can have with others a univocal agreement in some grade abstractable by the intellect as determinable or determining; but it is not repugnant that this be found in angelic natures, since they are of finite and limited perfection. You will say: therefore there is no difference in this between material and immaterial substances; because in both genus and difference are taken from the whole nature according to a more perfect or more imperfect grade; whence matter and form are related as it were per accidens, because they concur only in so far as they are parts composing such a nature; but the consequent seems to be against St. Thomas in the places cited, especially I, q. 50, a. 2, ad 1, where he says that there is a difference between material and immaterial substances, that in the former the genus is taken from one thing and the difference from another, but in the latter each is taken from one and the same thing according to diverse reason. Ferrariensis, above, answers that, if we speak of the proximate principle, there is no difference, because that is the whole nature in all substances, as we have said; but if the discussion is of the radical principle, in this there is some difference; for in immaterial substances, since they are not composed of physical parts, the radical principle of every formal unity is the same as the proximate; but in material substances, because they are composed of physical parts, although the whole nature is the proximate principle, matter is nevertheless judged to be the radical principle of the genus, because it is the root of all potentiality, and because the genus is considered as determinable through differences through proportion to it; but form is judged to be the first root of the difference, because it gives the ultimate perfection and brings the complete nature into act. In which some difference can also be considered between matter and form, because matter per se is not properly the radical cause of any grade, even generic, until it is actuated by the form, on which primarily and essentially every grade of substantial nature depends. Whence St. Thomas, question De spiritualibus creaturis, a. 1, ad 24, says that when the genus is said to be taken from matter, it is not to be understood of prime matter, but according as through the form it receives a certain imperfect and material being with respect to the specific, as the being of animal is imperfect with respect to man, and both are from the soul. Whence it comes about that, properly speaking, matter is not the principle of the genus except through analogy and proportion, as we have said. But the form seems to have something more with respect to any difference whatever, because it is its proper root, which is true not only of the ultimate but also of subaltern differences. Although matter is not altogether to be excluded in its genus, because every natural form is its act, and from it as such the difference is taken, and therefore matter is always in some way included in such a difference.

6. Material substances agree univocally with immaterial ones.—To the second there are not lacking those who concede the consequence, namely that there is no common genus to things not having common matter, or of the same notion, as was cited above. But they rest on no probable foundation, because, as we have shown, the composition of genus and difference is not repugnant to finite things, even if they either consist of no physical matter or of matter of another notion from the matter of these inferior things. Likewise it is not repugnant to them to have univocal agreement or likeness with these inferior things, as is evident of the concept of substance, which, considered according to its precise notion, belongs equally to integral material and immaterial substances, and to terrestrial as to celestial ones. The answer, then, to the argument is by denying the consequence; for first of all, as regards celestial and terrestrial bodies, although we grant that their matters are different in species, since those very matters agree in genus among themselves, it will be no inconvenience that from them in their own way one common genus be taken for these bodies, not only in so far as they are substances but also in so far as they are bodies. But as regards immaterial substances, they agree univocally with inferior ones in the notion of being per se or subsisting in a substantial nature; whence they can have a common genus, not taken from proper matter, but from the whole nature according to its indeterminate notion, as has been said. Nor is that Aristotelian saying repugnant to this truth, the corruptible and the incorruptible differ in genus, because, as St. Thomas, Alexander of Hales and others expound, both there and in Metaphysics V, text 33, that is not to be understood of the logical or metaphysical genus, which is considered through agreement in some formal unity, but of the physical genus, which is matter itself; of which interpretation more below, Disp. XXXIX, sect. 3. The third reason has been dissolved by what has been said.