Disputationes metaphysicae

1. What the material cause of metaphysics is.—What the formal.—What the efficient.—The object and essence of this science having been explained, it was fitting to say something about its causes; but since nothing proper and peculiar occurs to be said about the material, formal and efficient causes, we shall therefore speak only of the final cause. For the material cause of this science is none other than its subject, which it is evident is the intellect, unless someone wishes to reduce the matter about which it is concerned to the material cause; that matter, however, is none other than the object of the science, about which enough has been said. Again, since the science itself is a certain form, it has no other proper formal cause, but it has its essence, or formal notion; it has also an object, which, in so far as it gives the species, is said to have a certain notion of form, at least of an extrinsic one. Finally, since this science is acquired, it comes to be through its proper acts as through its proximate efficient cause, in which it has nothing special besides what is common to the other acquired habits. There remain, therefore, only the end and the function of this science to be explained; for these two are so conjoined in the present case that they seem rather to be one; this science, however, as regards the habit, is for the sake of its operation, which it proximately elicits; for this is common to every habit, nor does the habit of this science have anything in particular which needs new declaration. But concerning the operation or act of this science itself, it must be explained what kind it is, and what end it has, and from this it will be evident what the necessity or usefulness of this science is.

2. What the end of metaphysics is.—I say, therefore, first, that the end of this science is the contemplation of truth for its own sake. So Aristotle teaches, Metaphysics XII, c. 2, and Book II, c. 1, where he proves it, first, a priori, because that science is most of all for the sake of the knowledge of truth and for its own sake which considers the first causes and principles of things, and the most worthy things; for such things are most apt to be known, and their knowledge is most desirable; but this science is concerned with the knowledge of the highest things and causes, as is evident from what we have said about its object; therefore this science is most of all for its own sake, and for the sake of the knowledge of truth. Secondly, because this science does not inquire into the knowledge of truth for the sake of operation; therefore for its own sake; for there is no middle to be found between these. The antecedent, however, is proved by Aristotle by a twofold sign: one is that men began to find this science on account of wonder and ignorance of causes; therefore they sought it for the sake of knowledge, and not for the sake of some other work. The second sign is that men investigated this science when all things necessary for this life were available to them; they sought it, therefore, not for the sake of some other use, but to drive out ignorance, and thus for the sake of the very knowledge of truth. Thirdly, we can prove it because a science which orders knowledge to operation disputes proximately about things operable by man; but this science does not treat of things of this kind, but of the most noble beings, and of the most universal and most abstract notions of being.

3. But if anyone considers rightly, both the assertion posited and the things we adduced from Aristotle in its confirmation are common to all the speculative sciences, and most of all to natural philosophy; and so from the reasons given Aristotle rightly infers that this science is speculative and not practical, because it is not proximately ordered to work, but rests in the knowledge of truth, which (as I said) is common to the whole of natural philosophy; in order, therefore, that the proper end of this science may be declared in the assertion posited, it must be understood that it is for the sake of the knowledge of those truths which can be demonstrated about being itself as such, and about things which abstract from matter according to being. And so its proper end is to declare the nature, properties and causes of being in so far as it is being, and of its parts, in so far as they abstract from matter according to being.

4. And hence is gathered the first necessity or usefulness of this doctrine, namely, that it perfects the intellect according to itself (so to speak), and for the sake of knowing the most perfect things and notions of things. For the human intellect, although it is in the body, and therefore needs the ministry of the senses and of phantasms, is nevertheless spiritual according to itself, and has the power of perceiving all things, even spiritual and divine ones, on account of which it has been called in a certain way divine by Aristotle, De Anima I, text 82. Natural philosophy, therefore, seems to perfect the intellect as it uses the senses and is concerned with sensible things. The mathematical sciences seem to perfect it as it abstracts in some way from the experience of the external senses, yet with dependence on the imagination or phantasy. But this doctrine illuminates the intellect according to itself, abstracting, as far as can be done in the body, from the senses and the phantasy, and contemplating spiritual and divine things, and the notions and principles common to all things, and the general attributes of beings, which are considered by no lower science.

5. Secondly, however, it must be added that the science of metaphysics is not only fitting for its own sake, but is also very useful for perfectly acquiring the other sciences. This assertion is taken from Aristotle, Metaphysics I, c. 2, and Book III, c. 2, where among the other conditions of wisdom he posits that the other sciences minister to it, while it presides over the others, and (says Aristotle) commands them, not by practical command, which pertains rather to prudence or the moral sciences, but by speculative direction; and he adds that metaphysics is of this kind with respect to the other sciences because it disputes about the most excellent things, and about the first causes of things, and about the last end and the highest good. He adds also, Posterior Analytics I, c. 7, that metaphysics alone is concerned with the first principles of the other sciences. For there are two kinds of principles of the sciences, as he teaches in the same book, c. 8: some proper, which are declared in each science; others common to many, or rather to all sciences, because all use them as the subject matter demands, and in so far as the other particular principles depend on them, as the Philosopher says in the same place, and in Metaphysics IV, text 7. Since, therefore, all the sciences depend most of all on these principles, it is necessary that they be most of all perfected by this science; because, as was said above, the knowledge and contemplation of these principles can pertain to no special science, since they consist of the most abstract and most universal terms. Thus, therefore, this science is very useful for the attainment and perfection of the others. Hence St. Thomas, at the beginning of the Metaphysics, and In II, dist. 3, q. 2, a. 2, says that metaphysics is ordinative of the other sciences, because it considers the notion of being absolutely, while the others consider being according to a determinate notion; and In II, dist. 24, q. 2, a. 2, ad 4, he says that metaphysics directs the other sciences. Finally, from what we have said about the object and matter with which it is concerned, this can easily be proved, because this science considers the supreme notions of beings and their most universal properties, and the proper notion of essence and of being, and all the modes of distinction which are in things; but without the distinct knowledge of all these a perfect knowledge of particular things cannot be had. Which can also be known by experience; for all the other sciences often use the principles of metaphysics, or suppose them, in order to be able to proceed in their demonstrations or reasonings; whence it often happens that from ignorance of metaphysics errors are made in the other sciences.

6. Something is useful for another in many ways.—You will say: since this science of metaphysics is sought most of all for its own sake, how can it be useful for the others? For what is useful for other things is for their sake. The answer is: something happens to be called useful for another in two ways: in one way as a means ordered to another; in another way something is called useful for another as a superior and more eminent cause, influencing the other in its own way. In this latter way, therefore, metaphysics is useful for the lower sciences, and therefore it is not repugnant, but rather very consonant and consequent, that it be most of all for its own sake and very useful or profitable for the others. But in the former way the other sciences are ordered to metaphysics, in so far as all other knowledge, both speculative and practical, is ordered to the supreme contemplation in which the natural happiness of man consists. So, almost, St. Thomas, Contra Gentiles III,¹ c. 25, sixth argument, where he speaks thus: But first philosophy is related in this way to the other speculative sciences: for all the others depend on it, as receiving from it their principles and their direction against those who deny the principles; and first philosophy itself is wholly ordered to the knowledge of God as to its last end.²

7. But in order that these functions of metaphysics may be more exactly understood, it is necessary to declare in particular what the offices are which it exercises with respect to the other sciences, and how it carries them out.

How metaphysics is concerned with the objects of the other sciences, or whether it demonstrates them³

8. First, then, it is wont to be attributed to metaphysics that it prescribes its object to each science, and, if necessary, demonstrates that it exists; which Averroes indicated, De Caelo III, comm. 4, saying that it belongs to metaphysics to defend and verify (for so he speaks) the subjects of the particular sciences. The reason, however, can be that, as Aristotle teaches in Posterior Analytics I, a science does not prove, but supposes, that its object exists and what it is; therefore it must take this from elsewhere; therefore, since this is not always self-evident, and often needs some declaration and proof, it must take it from some superior science, which can be none other than metaphysics, to which it pertains to consider the notion of essence, of quiddity, and of being itself.

9. Objection.—You will say: how can metaphysics demonstrate about the objects of the other sciences that they exist? For if the discussion is of actual existence, this is not required in order that things be objects of a science, but is related as it were per accidens; whence it cannot be demonstrated, especially of created beings, since it does not belong to them necessarily; and if it can be proved in some way from effects, this seems rather to pertain to the natural philosopher, who philosophizes from sensible effects; but if the discussion is of being in aptitude, or in potency, this cannot be demonstrated of a subject, because there is no middle term by which it could be demonstrated; just as it also cannot be demonstrated of the subject of a science what it is, because there is no middle term by which its proper essence belongs to each thing, but it belongs to it immediately and of itself. Add that this science cannot descend to the particular objects of the individual sciences, because it cannot transcend its proper abstraction; just as, therefore, for this reason it cannot demonstrate their properties, so neither can it show whether they are or what they are. Moreover, if the other sciences needed the aid of this one in order to take their objects from it, they could not be learned before this science; which is false, as is evident from experience; for although this science is first in dignity, it is not first in generation. Finally, if it is necessary that this science demonstrate the objects of the others, another science will be necessary which serves this one in showing its proper object, because it itself cannot demonstrate that its object exists, but must suppose it, nor is that so self-evident as not to need some showing.

10. Answer.—To the first difficulty the answer is that this science helps the others to show that their objects exist, or what they are, in the same way as they themselves suppose this about their objects. But sciences, speaking per se, do not suppose that their object actually exists; for this, as the argument given proves, is accidental to the notion of science; I except that science which is about God, whose being is of his quiddity; but in other things their existence is not necessary for science and demonstration, except perhaps sometimes on our part for inquiring into and finding science, because we receive science from things themselves. This science, therefore, does not demonstrate that the objects of the others actually exist, but it can be said to show that the other objects exist only for this reason, that it provides principles for showing in which grade of beings such objects are placed, and what quiddity they have. This doctrine accomplishes this, however, by declaring, first of all, the very notion of being and of essence or quiddity, and in what it consists, and then by distinguishing the various grades of beings under which all the objects of the sciences are contained. Wherefore, although a priori and in itself it cannot be demonstrated through a proper intrinsic middle term that the object of a science exists and what it is, nevertheless as regards us it can be shown from signs or effects, by declaring, first of all, what is required for the notion of being, and in what the notion of essence consists, and what connection it can have with such signs or effects; all of which are exactly shown only through the principles of this doctrine.

11. Add also that through extrinsic causes, such as the final and efficient, it can sometimes be shown that some object exists, which is done most of all through the first and universal causes, about which this science considers; as we can show that angels exist, both because they are necessary for the perfection of the universe, and because they are of such a nature that it was not repugnant for them to be made by God.

12. And so it is also evident how this science can exercise such a function with respect to the objects of the particular sciences, even if they seem to be below its abstraction. For, first of all, as we touched on above in the second section, although metaphysics is not per se concerned with all things according to their proper notions, it nevertheless attains them in some way, namely, in so far as is necessary for explaining the proper notions, or handing down the divisions, and separating the proper metaphysical grades from the others; which metaphysical divisions serve the other sciences much for prescribing their subjects and separating them from the others. And next, it is not always necessary that metaphysics show the objects of the individual sciences immediately by itself, but it is enough that it provides the principles and declares the terms which the other sciences can use for supposing or showing, as far as is necessary, their objects.

13. Metaphysics is prior to all the sciences in the order of doctrine.—Why it is learned last.—Hence it must consequently be admitted that, if the order of doctrine is regarded according to itself, metaphysics is prior to the others, which can be gathered not only from this function, but also from another which we shall explain immediately; for it confirms in some way the principles of all the sciences. Next, it declares the transcendental notions of being, without the knowledge of which scarcely anything can be exactly treated in any science. And finally it has a certain singular connection with dialectic, which I shall declare below, by reason of which it has perhaps come about that a great part of this doctrine is treated confusedly by modern dialecticians. Nevertheless, by reason of our mode of knowing, this science has claimed for itself the last place, as is evident from the usage of all, and from the very title given by Aristotle; for on this account he called this science transphysical or post-physical. And the reason is that which St. Thomas touched upon, In Metaph. I, c. 1, lect. 2, and Avicenna, Book I of his Metaphysics, c. 3: because things which abstract from matter according to being, although according to themselves they are most intelligible, are nevertheless found by us only through motion, as is evident from Metaphysics XII. And similarly the most universal and most abstract notions of being, although according to themselves they are better known, especially as regards the question whether they are, nevertheless what they are, and what properties they have, is known by us with difficulty; and often it is necessary to begin from particular and sensible things in order that we may be able to reach them; and in this way Aristotle said, Metaphysics I, c. 2, that the most universal things are the most difficult to know. Hence, speaking of the order as regards us, it is not always necessary that this science be placed before the others; yet some principles of this science, or metaphysical terms, are always supposed, in so far as they can be known in some way by virtue of the natural light of the intellect, and as far as is sufficient for discoursing and proceeding in the other sciences, although not so exactly and perfectly as is done once this science has been acquired.

14. How a science supposes its object.—To the last confirmation it is said that this science surpasses the others in this, that it not only supposes that its object exists, but also, if necessary, shows that it exists, using its own proper principles, speaking per se; for per accidens it sometimes uses foreign and extraneous ones, on account of the excellence of its object and the defect of our intellect, which cannot attain it perfectly as it is in itself, but only from lower things. But when it is said that a science supposes that its object exists, this is understood speaking per se, as Cajetan noted, I, q. 2, a. 3; per accidens, however, it is not unfitting that some science should demonstrate its object as regards us. And if that science is supreme, it does not need the aid of another, but can accomplish this by its own power; and such is metaphysics in the order of natural sciences, just as theology too has this in the supernatural order.

How metaphysics confirms and defends the first principles

15. First reason for the difficulty.—Second.—Third.—The second chief function which is attributed to this science is to confirm and defend the first principles. Aristotle attributes this function to this science, Posterior Analytics I, c. 7, and Physics I, c. 1, and he hands it down and exercises it professedly in Metaphysics IV, c. 3, where all the commentators hand down the same; and Proclus, Book I of his Commentary on Euclid, c. 4, where he also says that metaphysics supplies principles to the mathematical sciences. But what kind of function this is, and why or in what way it pertains to this science, is not easy to explain. And the reason for the difficulty is, first, because the first principles are known per se, naturally, and without discourse; but this science, since it is essentially a science in all its parts, can in none of them be concerned except through discourse, and consequently with conclusions and mediate propositions; therefore it can exercise no proper function with respect to the first principles. Secondly, because otherwise the habit of metaphysics would be confounded with the habit of first principles, because metaphysics would usurp the proper function of that habit; whence it would not be necessary to distinguish them, contrary to Aristotle, Ethics VI, c. 3, where he distinguishes five virtues of the intellect, and among them places understanding, that is, the habit of principles, and wisdom, which it is evident from the same Aristotle, in the prooemium of this work, is metaphysics. The first consequence is evident, because it pertains to the habit of principles to give assent to the first principles with greater evidence and certitude than all science, since all the evidence of the sciences depends on that habit; therefore metaphysics cannot confirm the first principles, or add some strength to the assent to them, unless it usurps the function of the habit of first principles. Thirdly, because either this science exercises this function only by explaining the terms of which the first principles consist, and this is not the function of a science, nor is some judicative habit necessary for it, but only fitting apprehension and explanation of the terms; or it exercises this function by demonstrating the principles themselves in some way; and again I ask whether this is understood of a priori or a posteriori demonstration. And the first cannot be said, because the first principles as such are immediate, whence they cannot be demonstrated a priori. But if they are taken as they are not immediate as regards us, such as is that principle by which the first attribute is predicated of the thing defined, then it is not the function of one science to demonstrate such principles, but each science in its own matter demonstrates those which pertain to it, nor can metaphysics descend to each in particular, as is evident from what was said in the preceding sections. Therefore nothing proper can be attributed to metaphysics in this respect. But the second, about a posteriori demonstration, cannot more fittingly be said, because this kind of demonstration and science does not pertain to wisdom, such as metaphysics is, but pertains either to experience or to a posteriori science, which they call science of the fact, which is without doubt inferior, and a habit distinct from perfect science, because perhaps it is not one with respect to the first common principles and the proper principles of the individual sciences. Hence, just as there can be joined in us to perfect wisdom or metaphysics some imperfect habit demonstrating a posteriori the first common principles pertaining to metaphysics, so there can be joined to the individual particular sciences a similar proportioned habit, demonstrating the principles of each a posteriori; what is it, then, that metaphysics has proper and singular in this function?

16. The reasons for doubting proposed are resolved one by one.—We cannot answer this question and declare this function more conveniently than by briefly running through the difficulties proposed. And the first indeed is easy; for we grant that the function of this science with respect to the first principles is not to elicit that evident and certain assent which the intellect, led by natural light, gives without any discourse to the first principles sufficiently proposed; for that argument proves this rightly, and the second also confirms it. It will pertain, therefore, to this science to use some discourse about the first principles themselves, by which it confirms and defends them in some way; but in what way it accomplishes this will be declared in the second and third difficulties.

17. Concerning the second, some are wont to treat in this place whether the habit of principles, which Aristotle called understanding, is a quality distinct in reality itself from the intellective power, and whether it is a quality congenital by nature, or rather acquired. For those who deny that this habit is any quality besides the natural light of the intellect itself—which, in so far as by its nature it is sufficiently inclined to the assent to the first principles, is called their habit, and is distinguished from the faculty of understanding not really, nor from the nature of the thing, but by reason alone—those (I say) who think thus will easily dispatch the difficulty proposed, saying that metaphysics is distinguished from the natural light of the intellect, but not from another habit which could confer on the intellect some facility with respect to the assent to the first principles. To others, however (and indeed more probably), it seems that this question does not depend on that one; for whether the habit of principles is a distinct quality and acquired through acts, or not, it is necessary that metaphysics be a habit distinct from it, because, as I was saying in the first difficulty,⁴ the function of metaphysics cannot be to give simple assent, or assent without discourse, to the first principles. But those who posit that habit as a distinct quality say that its function and usefulness is to elicit together with the intellect, more promptly and more easily, the very simple and immediate assent to the first principles; therefore, even if we posit that the habit of principles is acquired by its proper acts, we ought not on that account to confound it with the habit of metaphysics.

18. These questions, therefore, are not connected, nor does one depend on the other. And (as I think) Aristotle posited both, namely, that the habit of principles is a virtue distinct from wisdom, as is evident from the cited place, Ethics VI, c. 3,⁵ and that it is a habit which we acquire by our acts, as can easily be taken from the same place and from Posterior Analytics II, last chapter. For in the former place he manifestly places it among the habits or virtues of the intellect; but if it were not a thing distinct from the faculty of understanding itself, it would be most improperly, indeed falsely, said to be a habit of the intellect. In the latter place, however, he thinks more openly that it is a habit, not implanted by nature, but acquired, not through discourse, but through simple acts gained from the mere proposition and understanding of the terms. And in truth this latter follows from the former. For if this habit were not some facility acquired by use for eliciting similar acts more promptly, there would be no reason or foundation why it should be judged to be some quality distinct from the nature of the thing from the natural light of the intellect, or from the faculty of understanding itself; both because, as Aristotle said, De Anima III, c. 4, the intellect by its nature is pure potency in the order of intelligibles, and as it were a blank tablet; and also because, if nature itself had given the whole power which is necessary on the part of the power for eliciting these acts, not only as regards their substance, but also as regards promptness and facility, it would have been superfluous to multiply entities in the faculty of understanding itself; rather, it could and should have been constituted stronger and more efficacious in its own intrinsic entity, nor would there be any indication for gathering that distinction of entities. Just as, if the will by its nature is so prompt and ready for loving the good in common that it cannot be rendered more prompt and ready through acts, it is the best argument that it does not have that promptness through an innate habit, but through its own entity. And similarly sight, because from its nature it has the whole inclination and efficacy which it can have on its part for eliciting the act of seeing, we rightly gather that it has that whole power and inclination through its intrinsic faculty and indivisible entity, and not through some other implanted by nature. Hence St. Thomas, I-II, q. 51, a. 1, thought that this habit is not natural according to itself, but as regards a certain beginning, namely, because the acts through which it is acquired are not had through discourse, but flow immediately from the very light of nature, although in the beginning and before the habit they do not emanate with as much promptness and facility as after the habit has been acquired; concerning which matter we disputed at length on Posterior Analytics II, and perhaps we shall add something in what follows.

19. How metaphysics is concerned with the first principles, and how the habit of principles.—This opinion, therefore, being supposed, to the second difficulty the consequence is denied. For metaphysics is concerned with the first principles otherwise than the habit of principles. For, first of all, metaphysics is not concerned with the first principles formally, as they are principles, but as they are in some way conclusions. But the habit is concerned with the principles formally, as they are such, and immediate truths; and therefore this habit attains them without discourse, but metaphysics by means of some discourse. Hence, again, the habit of principles does not properly add some evidence or certitude to the assent to the principles, which can be had from nature alone, but adds facility and promptness in exercising that evidence and certitude; but metaphysics adds certitude and evidence, because it makes one assent to the same truth in a new way and through a new middle term. It is, however, to be considered attentively that this increase is not intensive but extensive. First indeed, because metaphysics does not increase the evidence or certitude, nor even the intension, of the very assent which the habit of principles elicits, because, as I said, metaphysics in no way operates about that assent, but about its object or matter provides a new mode of assenting, by a distinct act, of course. Secondly, because if we compare these acts among themselves, the assent of metaphysics is not in truth more certain or more evident than the assent of the habit of principles, as the argument given proves, because it is always necessary that the assent of metaphysics rest on some first principles as self-evident. And for this reason we say that metaphysics does not increase intensively the evidence or certitude about the first principles, but only extensively, by providing a new evidence and certitude of them.

20. The knowledge of the terms contributes most of all to knowing complex principles.—Concerning the third difficulty, another question is touched upon, namely, in what ways metaphysics is concerned with the first principles, by helping and confirming the intellect in its assent to them. In which it must be said briefly that this doctrine accomplishes this function in the two ways indicated in the third difficulty. For, first of all, it hands down and declares the notion of the very terms of which the first principles consist. Which is evident almost by experience itself in the course of this doctrine, both in Aristotle, especially in Books V, VII, VIII and IX, and also in other authors, and it will be evident from what we shall say in the following disputations. For in this science it is handed down what being is, what substance, what accident; what a whole, what a part, what act, what potency, of which terms, and of others similar, the first principles consist. For since these principles do not have in reality an intrinsic and as it were formal middle term by which their extremes are connected, they are known of themselves from the knowledge of the terms; whence nothing can help more toward their knowledge than a scientific and evident knowledge of the terms, or of their notions, such as is that which is handed down in this science. For it is not true, what was assumed in the aforesaid third difficulty, namely, that this function does not pertain to science, which proceeds by discoursing and judging, but to the simple apprehension of the terms; for although, speaking per se, on the side of simple things and terms demonstration is not required, nor even composition, in order to understand what each thing is or signifies, nevertheless as regards us this can often be demonstrated, especially by using a division consisting of opposite members, and by demonstrating what the thing is not (which is frequently better known to us), and thence concluding what it is. Often also this is done by handing down some descriptions of the simple notions which are better known as regards us, and using them as middle terms for making demonstrations, which sometimes suffice for acquiring human science. And hence, finally, it is understood that this mode of illuminating the first principles is exercised chiefly and immediately in this science with respect to those first principles which are most universal and consist of more abstract terms, that is, terms signifying things, or notions of things, which can exist without matter; for, as we said, these are the ones which, speaking per se, are contained under the object of metaphysics; and since it is the supreme science, it is per se sufficient for handing down and explaining the notions of all the things and terms which are enclosed under its object. But it does not descend so proximately and immediately to the proximate and particular principles of the individual sciences, and to the terms of which they consist, but attains them only in one of the two ways explained above, namely, either in so far as is necessary for handing down the proper definitions and explaining the proper terms, or in so far as general, and especially transcendental, notions are included in them, without whose knowledge and aid no notion or quiddity of any thing whatever can be explained in particular.

21. The most universal principles cannot be demonstrated through causes.—The other way in which this science is concerned with the first principles is by demonstrating them, or their truth and certitude, which it can accomplish in various ways. First, some say that metaphysics demonstrates the principles a priori, not indeed through an intrinsic formal or material cause, because (as the argument given rightly proves) in these immediate principles such a kind of demonstration has no place, but through an extrinsic cause, final,⁶ efficient and exemplar; for since metaphysics considers the first causes, even God himself, who, as he is the first truth, so is the cause of all truth, at least an extrinsic cause in all the aforesaid ways, it can at least through this cause demonstrate the truth, not only of the first principles, but also of the conclusions. This mode of demonstrating, however, is very rarely or never exercised in this doctrine, and if it is considered more attentively, it can scarcely have a place. For, first of all, as regards the efficient cause, this has no place in the most universal principles consisting of terms common to God and creatures; for just as with respect to God no efficient cause can be given, so neither with respect to those principles which have truth in God himself, such as that: Anything whatever either is or is not, and: It is impossible to affirm and deny something of the same thing. And hence it is also evident that these principles cannot be demonstrated through the final cause, because the final cause is in order to effecting and operation, and therefore things which abstract from the efficient cause abstract also from the end. Again, hence it seems to come about that even those principles which are common only to creatures, in so far as they fall under science, cannot be demonstrated through the efficient or final cause, because as such they abstract from actual existence, and consequently from efficiency; for all efficiency is about an existing thing, or one which is brought to issue; as, for example, every whole is greater than its part is true, all efficiency being set aside, and so of the rest. And hence, further, proof through the exemplar cause does not seem possible here, both because what abstracts from the efficient cause abstracts also from the exemplar; for the exemplar is that to whose likeness the efficient cause operates, and it is compared as art, or the notion of operating, with respect to an intellectual efficient cause; if, therefore, the truth of these principles abstracts from the efficient cause, it also abstracts from the exemplar cause; and also because the essence of things as such does not depend on the exemplar cause; therefore neither does the truth of the first principles. The antecedent is evident, because man, for example, is not a rational animal because God knows him as such, or because he is represented as such in the divine exemplar, but rather he is known as such because of himself he demands such an essence.

22. An objection is met.—But to these things it can be said that these principles abstract indeed from actual efficiency, but not from possible efficiency, and consequently do not altogether abstract from the efficient, exemplar and final cause; for, as we shall say below, although the essences of creatures can be abstracted from being, they cannot be abstracted from order to being, without which a true and real essence cannot be understood; by the same reason, therefore, the first principles common to true and real created beings, even if according to their necessary connection they abstract from time and actual existence, do not abstract from order to being, namely, because with such a connection they could exist, and not otherwise; and in this way they can also have a respect to the aforesaid causes, and be demonstrated through them. As if someone proves that every whole is greater than its part because it can be made so by God, and not otherwise; or that the essence of man is rational animal because it can be established by God in that essence, and not in another. And similarly from the final cause it can be shown that man is a rational animal, because he can be instituted for knowing and loving God. Or from the exemplar cause, because he is represented as such in the divine idea. For man would not have such a real essence unless he had such an exemplar in God; nor is it repugnant that under diverse notions both be true, namely, both that God knows that man is of such an essence because he truly is such, and that man has such an essence because he has such an idea in God.

23. This answer indeed declares that this mode of demonstrating is not always impossible nor useless. For although these modes of demonstrating do not all have a place in each first principle—for it is not necessary that three and four being seven should have a final cause, and so of the other principles in which there is truth from the connection of the extremes, not indeed ordered to some end, because the predicate does not declare some property or essence of the subject, but rather identity, or the repugnance of opposites, as is evident in this: Anything whatever either is or is not, and the like, in which the said modes of demonstrating through extrinsic causes have no place—nevertheless they can be applied to many principles, especially that demonstration which is through the final cause; for the essences of things and their properties have a final cause, through which they could be demonstrated, if such a cause were otherwise self-evident, or could be shown through another better-known principle; for this is necessary in every demonstration.

24. Natural light cannot demonstrate through the first efficient cause, end and exemplar.—I add, however, further, that this kind of proof often exceeds the power of the natural light of the human intellect, and pertains rather to a divine (so to speak) or supernatural metaphysics than to a natural one. For the divine exemplars, unless they are seen in themselves, cannot be the reason or means of knowing some truth; but they cannot be seen in themselves through natural metaphysics; indeed, this science cannot show that God has these or those exemplars of things except a posteriori from the things themselves, just as from the workmanship effected in a thing⁷ we know what idea the craftsman had. And the reason is the same concerning the first efficient cause; for as long as we do not know the power of God in itself, we cannot know from it what things can be made by it, but rather we investigate the power of God from the things made, although, once the power of God has been known from certain effects, it can be demonstrated through it what he can do in others. And similarly from his perfection and efficiency we can investigate the end and perfection of his works, as that it belongs to him to establish all things for his own sake, or to make the universe perfect. From which we can further gather what natures he has attributed to the things known; which mode of philosophizing Aristotle touches upon, Metaphysics XII, at the end.

25. Demonstration by reduction to the impossible is the function of the metaphysician.—Besides these modes of demonstrating, which are little used, there is another, by reduction to the impossible; and in this way all principles are shown by reduction to that one: It is impossible to affirm and deny the same thing of the same thing at the same time. And because this is the most general principle, proper to this doctrine, this kind of demonstrating therefore pertains to this wisdom; but about that principle and its use we shall say more below, Disp. III. Finally, for increasing this certitude about the first principles, the consideration of the intellectual light itself, by which the first principles are manifested, can contribute very much, together with reflection upon it, and reduction to the source from which it flows, namely, the divine light itself. For thus we rightly gather that the first principles are true, because they are shown to be true immediately and per se by the natural light itself; because in this mode of assenting this light cannot be deceived, or incline to the false, since it is a participation of the divine light, perfect in its genus and order. Whence that saying of Psalm 4: Who sheweth us good things? The light of thy countenance, O Lord, is signed upon us. Hence Aristotle, at the beginning of the science of the soul, judged that science to be very certain because it contemplates the intellectual light itself; in which this wisdom surpasses that science; for it considers in a higher way the power and perfection of this light according to itself, in so far as it abstracts from matter according to being, and in so far as it participates the certitude and infallibility of the divine light.

26. How reduction to the impossible is an a priori demonstration, and how a posteriori.—You will say that a showing of the first principles of this kind is not a priori, but only a posteriori; for these principles are not true because they are known through an infallible light, but rather, because they are true and immediate, therefore they are manifested through such a light. I answer by granting that this proof is not a priori, if the truth of the principles is considered in the being of the thing (so to speak); it can, however, in some way be called a priori in the notion of the knowable, or of the evident and certain; for it is rightly shown a priori that some proposition is certain because it is revealed by God, or that it is evident because it is proved by demonstration. Thus, therefore, it can be shown that these principles are most evident, because they are manifested immediately by the natural light itself. And this proof and reflection contributes most of all to confirming the intellect and increasing its certitude, at least on the side of the subject, in the assent to the principles.

27. Inference.—From these things, therefore, it has been sufficiently declared how the first principles are contained under the object or matter with which this science is concerned, and what function it exercises with respect to them. And it can also be gathered in passing that this is indeed true of the first and most universal principles, but not of them alone, as Soncinas and Javellus and some others would have it; because, although, speaking per se, this doctrine is concerned more immediately with the former principles, and demonstrates them in more ways, as is evident from what has been said, nevertheless it also extends itself to the others, because some of the aforesaid modes are general and common to all. And therefore Aristotle spoke absolutely of all, saying that metaphysics demonstrates the principles of all the sciences, as is evident from the prooemium, cc. 1 and 2, and from Metaphysics IV, text 7, and from Posterior Analytics I, c. 7, and from Topics I, c. 2, and Physics I, c. 2, where he says that if anyone denies the first principles of geometry, it does not pertain to geometry⁸ to prove them, but to the first philosopher. And it is the open opinion of St. Thomas, I-II, q. 57, a. 2, especially ad 1 and ad 2. And by reason it can easily be shown from what has been said, for the modes of showing the first principles have a place also in the particular and proper principles of the other sciences. Indeed, St. Thomas adds in the cited place that it pertains to this science not only to confirm the intellect in its assent to the principles, but also to the conclusions; which can be understood remotely and mediately, because by confirming the principles it also virtually confirms the conclusions; or only materially (so to speak), because sometimes wisdom can show through higher causes conclusions which are demonstrated through other lower middle terms in the other sciences.

That it is not the function of metaphysics to hand down the instruments of knowing

28. The opinion of some.—There are those who think that this function too pertains to metaphysics. For although the dialectician teaches to define, to divide, etc., he nevertheless cannot declare instruments of this kind from their proper principles and render their reason, but can only hand down and set out instruments of this kind as regards the question whether they are; but it pertains to the metaphysician to discourse about them, declaring their first roots and causes. Which can be set out of each thus: for definition declares the essence of the thing; but to declare the notion of essence pertains to metaphysics. Therefore to hand down the perfect notion of definition too is the function of metaphysics. Again, division declares distinction; but to deal with the distinctions of things is the function of metaphysics; therefore to explain the notion of division too pertains to it. Moreover, the whole force of argumentation, if we look to its form, consists in one of these principles: Things which are the same as one third thing are the same as each other. The same thing cannot at the same time be affirmed and denied of the same thing. But these principles are proper to the science of metaphysics, to which it pertains to treat of the same and the diverse, and of being and non-being, which are explained through affirmation and negation; therefore on this head too it pertains to the metaphysician to hand down the instrument of knowing. Finally, science is a spiritual quality; therefore as such it is comprehended under the object of metaphysics; therefore by the same reason it pertains to metaphysics to hand down the notion of acquiring science, and to declare by what modes or instruments it is acquired; for to deal with the end and the means belongs to the same doctrine; but all these are ordered to science as to their end.

29. It is rejected.—But this opinion, unless it is declared more fully, confounds metaphysics with dialectic, for it is the proper function of dialectic to hand down the mode of knowing, which it does in no other way than by teaching the instruments of knowing, and demonstrating their force and properties. Wherefore, in order that we may set out what the truth of the matter is, and attribute to each science its proper function, it is to be noticed that these instruments of knowing are found properly and formally in the thoughts of the mind, or the internal acts of the intellect, but are founded in things, and explained by words. For science consists in some act of the intellect, or in a habit, according to the diverse acceptations of science, namely actual and habitual; and therefore it is necessary that the proper instruments of knowing be placed in the intellect itself and in its acts; for, since man acquires science through discourse, and needs other prior operations or conceptions of things in order to complete discourse, therefore conceptions of the mind of this kind, so disposed and ordered as to contribute per se and directly to acquiring science, are called instruments of knowing; instruments of this kind, therefore, are formally in the operations of the mind. Since, therefore, the operations of the mind, in order to be right and true, must be proportioned and commensurate to things themselves, it is therefore necessary that instruments of this kind be founded in some way in things themselves; they are explained, however, by words, which have been given by nature for expressing the thoughts of the mind, according to that saying of Aristotle, Peri Hermeneias I: Those things which are in the voice are signs of the passions which are in the soul; and that of Cicero, De Oratore I: In this one thing we excel the beasts, that we speak among ourselves, and that we can express our thoughts by speaking.

30. The true opinion on this.—It belongs to dialectic to treat whether the instruments of knowing are, and what they are.—Thus, therefore, it must be said that it does not pertain to the metaphysician directly to hand down the instruments of knowing, and to teach the mode and disposition which they must have in the concepts of the mind in order to be apt for generating science. This is proved by the argument indicated above, because this pertains to the function of dialectic; for which reason Aristotle said, Metaphysics II, c. 3, that it is absurd to seek at the same time science and the mode of science. By which words he wished to teach (as all the expositors hand down) that dialectic is to be acquired before the other sciences, especially before metaphysics, because it pertains to it to hand down the mode of knowing; which is nothing other than to teach the instruments of knowing, and to lay open the mode of treating and proving things accommodated to science. Nor is it true that dialectic explains these things only cursorily, and as regards whether they are (as they call it), both because it is evident from experience that dialectic hands down not only the laws of rightly defining, arguing or demonstrating, but also the reasons of these things; for it also demonstrates a priori why a right definition and argumentation require such conditions and properties, and similar things; and also because otherwise dialectic would not be sufficient for acquiring science, but it would be necessary also to place metaphysics before it, which is plainly false, and against the sense and usage of all. The consequence is evident, because true science is never acquired unless one knows that one knows; for science must be a perfect intellectual light, which manifests itself, otherwise it will not be altogether evident; but one cannot know that one’s knowledge is true science unless one knows that one’s reasoning is a true demonstration, which one cannot know unless one knows what a true demonstration is, and why it must consist of such principles and such a form of reasoning. If, therefore, dialectic did not render the reason of all these things, but rather demanded a certain faith in them, it could not serve, or be sufficient, for acquiring true science. And it is confirmed, because a demonstration is not an apt instrument of knowing unless it is known as a demonstration, that is, as a reasoning necessarily concluding from certain and evident principles. For if someone composes an argument which in itself is a demonstration, but is not known as such by him, but is thought to be a probable argument, or one proceeding only from certain, but not evident, premisses, it will not generate true science in him, because such a demonstration so proposed is either an inept instrument, or not sufficiently applied to such an effect. Hence dialectic hands down the mode of knowing in such a way that it teaches it scientifically; on account of which those who think rightly about it judge it to be not only the mode of knowing, but also a true science; this function, therefore, pertains properly and per se to dialectic, and not to metaphysics.

31. Corollary.—And hence it also comes about that it belongs to the same dialectic, and not to metaphysics, to hand down or direct instruments of this kind as they can be expressed or composed by words (under words, however, we include writings, because as regards this they differ only materially); indeed, not even dialectic itself is concerned with these directly and by design as with its proper object and matter, but accomplishes this consequently, and as it were by a certain concomitance. For since words arise from concepts, while dialectic directs and orders the concepts, it consequently teaches by what words, or by what form of words, they are to be expressed in order that they may have the force of persuading and demonstrating; which whole matter is both clear of itself and perspicuous from the very use of dialectic.

32. Metaphysics illuminates the instruments of knowing very much.—It must be added, however, that, in so far as these instruments of knowing are founded in things themselves, their science and knowledge is very much perfected through the science of metaphysics, so that what we said metaphysics accomplishes with respect to all the sciences and their principles has a place by a certain peculiar reason with respect to dialectic and its functions. The reason for doubting posited at the beginning proves this, and it is declared in this way. For the knowledge of essence and quiddity as such pertains peculiarly to metaphysics; but definition, whose notion and form dialectic hands down, if it is perfect, explains the essence and quiddity of the thing; and therefore, while metaphysics hands down what the essence and quiddity of each thing is, it contributes very much to the perfect mode of defining. Especially because metaphysics hands down not only the notion of essence in common, but also, within its abstraction, declares the various grades and modes of essences; on which it most of all depends to know of what parts the definitions of things ought to consist, or what mode of defining it is necessary to hold in distinct things (for example, in substance or accident, and in a simple or a composite thing). Thus, therefore, metaphysics very much perfects the art of defining, although it does not hand it down directly and by design. In a similar way it happens with respect to another instrument of knowing, which is division, whose laws and conditions dialectic hands down; but all of them are founded in the distinction or opposition of things; but to deal with the various distinctions of things pertains to metaphysics; for the same and the diverse are reduced to the properties of being, as are one and many; and therefore, while metaphysics exactly declares the various distinctions of things, it also illuminates the art of dividing. But concerning argumentation or demonstration the reason does not seem similar, because it is not founded proximately in the essence, or in some property of being, as definition and division are; nevertheless by another way metaphysics helps dialectic in this function too, both on the side of the matter and on the side of the form. On the side of the matter indeed, because, while metaphysics distinguishes and separates the notions of almost all beings, and declares in general what the thing is in its essence, and what its properties are, what is a thing and what a mode, it ministers the matter for demonstrating and arguing, or rather declares exactly what both the extremes and the middle terms of a demonstration must be; on the side of the form, however, because this doctrine exactly declares and shows all the principles on which every right form of arguing rests, such as those: Things which are the same as one third thing are the same as each other. The same thing cannot at the same time be affirmed and denied of the same thing, and the like.

33. The arguments for the opposite opinion are solved.—To the reasons for doubting posited at the beginning the answer is easy from what has been said. To the first, about definition, the answer is that the metaphysician indeed declares in common what essence is, and also what kind it is, whether simple or composite, within the breadth of his object and his abstraction; but the dialectician treats of the mode in which the essence and nature of the thing is to be conceived by us and declared distinctly through definition, or of what concepts or words the definition is to be composed, or what properties it must have in order to be apt; these functions, however, are distinct, although they help each other mutually; for dialectic helps metaphysics as the mode of knowing helps science; but metaphysics helps dialectic as a general science which discourses proximately and exactly about things, which dialectic either supposes or attains only remotely. And almost the same answer is to be applied to the other part, about division;⁹ for metaphysics treats of the distinctions of things as they are in things themselves; but dialectic of the mode of conceiving and explaining the partitions of things. Similarly, to the third member, about argumentation, it must be said that, although metaphysics in some way demonstrates those principles, and reduces them to that most universal one: Anything whatever either is or is not, or: It is impossible for the same thing at the same time to be and not to be, dialectic too supposes a similar principle as self-evident, namely, that the same thing cannot be affirmed and denied of the same thing, to which it reduces almost the whole force and form of right argumentation, in order to demonstrate its properties and conditions.

34. To which science the treatment of science pertains.—To the last member, about science, the answer is that the consideration of science, as it is a certain spiritual quality and habit of the mind, or an operation of it of such a condition and nature, can be manifold. One is merely speculative, by which we contemplate what such a thing is, and what properties it has; and this consideration pertains either to that part of natural philosophy which treats of the rational soul, if the discussion is only of human science, which is not without phantasy; or, if we speak abstractly and absolutely of science, it will pertain to metaphysics, for it is a thing or property abstracting from matter according to being. Another consideration of science is as it were practical and artful, which is not about the habits but about the acts of science; for art is concerned with operations; and this consideration has a place only in human science, which is completed through composition and discourse; for art is not concerned with simple things, but with composite ones; for the aim of art is to direct some composition or harmony, whence the artful form arises from the due proportion and composition of parts or simple things; this direction and consideration of science, therefore, pertains to dialectic, which is the art of knowing, and not to metaphysics. In order, however, that dialectic may exercise this function, it is not necessary that it speculate exactly about the whole nature and essence of that quality which is science, but it is enough that it suppose that it is an operation of the mind, and hand down some of its properties which it requires for manifesting truth exactly and without error, such as that it be evident, certain, and the like. And this knowledge of science is handed down by the dialectician, as is evident from the books of the Posterior Analytics, and it suffices for the dialectician in order that he may direct his art and method of knowing to it as to his end. Finally, another consideration of science can be called moral, in so far as the use or exercise of science can be worthy of praise or blame; which function pertains to moral philosophy or prudence.