Jacques Maritain Center: Thomistic Institute

Aristotle and Aquinas on the Division of Natural Philosophy

Marie George

I intend to do two things in this paper. My main goal is to show to what extent Aquinas takes inspiration from Aristotle in his exposition of the division and method of that part of natural philosophy that treats living things. A secondary goal is to briefly compare some of Aquinas's views on these matters with the way studies of living things are divided and pursued nowadays.

A recommended reading on these topics is Charles De Koninck's "Introduction to the Study of the Soul." Note also that I will sometimes refer to "the part of natural philosophy which treats animate things" as "philosophical psychology" for the sake of brevity.

Aquinas's treatment of the division and method of the part of natural philosophy which treats animate things is found in the prooemium to his commentary on De Sensu et Sensatu.(1) Aquinas begins by dividing speculative philosophy into its parts:

1 As the Philosopher says in the third book of the De Anima, as things are separable from matter so also are the things that relate to understanding.(2) For anything whatsoever is intelligible insofar as it is separable from matter. Whence those things which are according to nature separated from matter are in themselves intelligible in act; those things which are abstracted by us from material conditions become intelligible in act through the light of our agent intellect.(3)

And because the habits of a power are distinguished in species according to the difference of that which is the per se object of the power,(4) it is necessary that the habits of the sciences, by which the intellect is perfected, also be distinguished according to the difference of separation from matter; and therefore the Philosopher in the sixth book of the Metaphysics distinguishes the genera of the sciences according to the diverse mode of separation from matter. For those things which are separated from matter according to being and reason pertain to metaphysics; those, however, which are separated according to reason and not according to being pertain to mathematics; those which in their very notion concern sensible matter pertain to natural philosophy. (5)

After Aquinas explains the main division of the speculative disciplines, he applies the distinction which is at the basis of that division to natural philosophy:

2 And just as the diverse genera of sciences are distinguised according to this that the things are separable from matter in diverse ways, so even in the particular sciences, and chiefly in natural science, the parts of the science are distinguished according to the diverse manner of separation and concretion.

The "chiefly" is significant, and I will come back to it latter. Aquinas continues with a most puzzling statement:

And because universals are more separated from matter, therefore in natural science one proceeds from the [more] universal to the less universal, as the Philosopher teaches in the first book of the Physics.

I say that this statement is puzzling because the I.1 Physics teaches that we go from the more universal to the less universal because our minds go from potency to act. We arrive first at a vague understanding of things because our minds start from sense experience from which the intellect is unable to immediately gather a clear understanding of the natures of the things which present themselves to sense.(6) The universals we first arrive at are less perfectly separated from matter; it is the imperfection of the separation which the intellect makes that accounts for the vagueness of our first knowledge.(7)

There is a sense in which the more universal are more separated from matter, and this can be gathered by reading further along in the prooemium:

Whence also natural science begins to teach from those things which are most common to all natural things, which are motion and the principle of motion, and then proceeds through the mode of concretion, or application of common principles, to certain determinate mobiles, of which certain are living bodies: concerning which one also proceeds in a similar mode distinguishing this consideration in three parts. For indeed one first considers the soul in itself, in a certain abstraction. Secondly, one considers those things which belong to the soul according to a certain concretion, or application to the body, but a in general way. Thirdly, one pursues the consideration by applying all these things to individual species of animals and plants, determining what is proper to each species. The first consideration, therefore, is contained in the book, De Anima. The third consideration is contained indeed in the books which he writes about Animals(8) and Plants. The middle consideration is contained in the book which he writes concerning certain things that belong commonly either to all animals or to the greater number of the genera of them, or even to all living things, concerning which is the present intention of this book.

In the Physics Aristotle treats the things which are most common to all natural things, one of the most important of which is motion. In treating motion, Aristotle speaks about act and potency and about the need for a terminus a quo and a terminus ad quem. What he says applies to all motions while prescinding from what is proper to any specific motion, e.g., from the apple ripening from green to red. In order to understand specific motions such as the apple's ripening one has to consider the matter undergoing the change, i.e., the parts involved, their physiology and biochemistry. Similarly in the case of the motions of animals, as Aristotle points out:

We have inquired elsewhere into the details of the movement of the various kinds of animals, the difference between these movements, and the causes of the characteristics which each exhibit; we must now inquire generally into the common cause of animal movement of whatever kind--for some animals move by flight, some by swimming, some by walking, and others by other such methods. Now that the origin of all the other movements is that which moves itself, and that the origin of this is the immobile, and that the prime mover must necessarily be immobile has already been determined when we were investigating whether or not eternal movement exists, and if it does exist what it is. It is necessary not only to grasp what is common in reason, but to grasp the common in regard to each particular and in the things known through sense, on account of which we seek the common notion (logos) and with which we think it is necessary that these notions agree. For it is clear also that movement is impossible if there is nothing in a state of rest, and above all in the animals themselves. For if any one of their parts moves, another part must necessarily be at rest.(9)

One cannot simply deduce what part of the animal is immobile, although one knows that there has to be such. One has to look at the material parts that make up the animal to discover that. In addition to this need to examine the matter in natural philosophy as one moves from the general to the particular, is another somewhat different need to do so which is specific to understanding natural living things. As Charles De Koninck explains:

It is not by pursuing the division of the soul into species that will allow one to attain living things in their specific concretion. The living natural thing is a mobile being, the animal is a living being, the elephant is an animal; but the natural living thing is not a soul, the animal is not the sensitive soul, nor the soul of the elephant an elephant. In the study of the living thing, the concrete application which in the treatise on the soul proceeds gradually towards the treatises on animals and plants, does not consist in a simple passing from the general to the particular. In the first treatise, we study the soul in an abstraction which is in nowise expressed by its generality alone.(10)

Soul then stands to the different types of soul as abstract to concrete in the sense of universal to particular, whereas soul stands to specific living things as abstract to concrete in another sense.

Why does Aristotle takes up the soul first rather than living things? He does so because living bodies are living bodies not because they are bodies, but because they possess soul. Possessing soul is something all living things share in common as living. And just as the definition of motion abstracts from the concrete conditions of any given type of motion, so too the definition of soul abstracts from the concrete conditions in which the different types of souls exist. This is not to say that the general definition of soul abstracts entirely from matter, any more than the definition of motion does. The soul is a form that exists in a determinate manner, whence Aristotle's pointed criticism of his predecessors for treating the soul without any consideration of the body of which it is the act.(11) It is only to the extent that the soul is a form in matter that it falls under the consideration of the natural philosopher.(12) This is why Aquinas says that Aristotle in the De Anima treats the soul in a "certain" abstraction.

The general definition of the soul, valuable though it is, only tells one in a general way what the soul of any type of living thing is. As Aristotle puts it:

Hence it is absurd...to demand an absolutely general definition, which will fail to express the peculiar nature of anything that is, or again, omitting this, to look for separate definitions corresponding to each infima species. ... Hence we must ask in the case of each order of living things: What is its soul, i.e. What is the soul of plant, animal, man?(13)

This process from general definition of the soul to the definitions of the three main types of soul is not by way of deducing the latter from the former. The only way of going from one level of concreteness to another is by recourse to experience. Although what is demonstrated about the soul is true of each the these three types of soul, it is true of them insofar as they are souls, not insofar as they are a specific type of soul. Not only is this true, but once again as De Koninck points out, given that one is ultimately trying to understand the nature of the different sorts of living things, and not just their souls:

one sees quite well that the term 'concretion' must be understood in a more rigorous sense than that of the passage from the general to the particular: it is no longer a simple comparison of the abstract and the concrete according to the order of predication, but the soul which in its proper nature relates to the living body as that by which this thing is living and by which it is this sort of living thing. Having studied the nature of the memory in a certain abstraction, one must seek to know which are the animals that are endowed with it, and what exactly its corporeal instrument is, and how and of what it is constituted, and how it functions; and the desire of perfect science carries us to seek the difference, even as to the organ, between the memory of elephants and that of bees.(14)

Let us now inquire why Aquinas says that it is "chiefly" in natural philosophy that the parts are distinguished according to the diverse mode of separation from matter. Consider how the other sciences relate to matter: mathematics abstracts from sensible matter; metaphysics treats being insofar as it is separable from matter.(15) Certainly, arithmetic is more abstract than geometry, because it does not take in account position as geometry does. However, within the mathematical disciplines there is no movement from more abstract to more concrete. Sometimes there is a movement from general to specific, as is the case when the conclusion of a proposition concerning triangle is used in a subsequent proposition concerning isoceles triangle (as is the case in Euclid, Book I, propositions 5 and 6). However, the movement to the particular here is not one which takes matter more into account. As for metaphysics: what it studies is being qua being and the principles and causes thereof. When it treats of material substance, it does so in order to understand something about the nature of substance.(16) And since material substances are best known to us, metaphysics starts by examining them and then moves towards immaterial substances which are better known in themselves, but less know to us.(17) The proceeding then is away from what is material, which is only taken as a starting point because it is better known to us. It is natural philosophy that considers sensible matter, for natural things are composites of both matter and form.(18)

In light of the above, it makes sense to say that because natural science procedes from the more universal to the less, (as Aristotle teaches in the Physics), in natural science one in fact first treats things which are more separated from matter, for these are more universal (e.g., the soul) and then procedes to things which are less separated from matter, for they are the less universal (e.g., the specific parts specific living things need in order to exercise their life activities). Having a sensitive soul is more commonly shared among living things than being capable of flight; and understanding flight requires investigating the material wings are made from. Thus while the more universal is more material in the sense that this knowledge does not allow us to know the natures of the infimae species which are what are most in act; it less material in the sense that in the case of natural things knowledge of species requires an understanding of matter as well of as form,(19) and the first universals we form in regard to living things (such as the notion that they have souls) abstracts from this matter.

True as this may be, it leaves unexplained explain why Aquinas says that "since the more universal are more separated from matter, therefore in natural science one procedes from the more universal to the less universal, as the Philosopher teaches in I Physics."

Returning to Aquinas's commentary: Aquinas explains what the middle treatises cover by showing how they bear on the four grades of livings thing outlined by Aristotle in II DA c. 3:

3 Whence it is to be considered that in the second book of the De Anima he determined four grades of life. The first of them is that which only has the nutritive part of soul, through which it lives, as is the case of plants. There are certain living things, however, which along with this also have sense without progressive motion, as is the case of imperfect animals such as shellfish. There are others which have in addition progressive local motion, as is the case of perfect animals such as the horse and the cow. There are others that in addition have intellect, as is the case of humans. For although the appetitive is posited as a fifth genus of power of soul, nevertheless it does not constitute a fifth grade of living thing, since it always accompanies sensation.

He then explains why there is no natural treatise that deals with the intellect and the intelligible:

4. Of these powers, however, the intellect is not the act of any part of the body, as is proven in the third book of the De Anima:(20) whence it cannot be considered through concretion or application to the body or to some bodily organ. The most concrete form of intellect exists in the soul; the highest form of it exists in separated substances. And therefore Aristotle does not compose a book on the intellect and the intelligible apart from the De Anima: or if he would have done so, it would not pertain to natural science, but rather to metaphysics, to which it belongs to consider separated substances.(21) All the other powers are acts of some part of the body: and therefore there can be a special consideration of them by application to the body or bodily organs apart from the consideration which is made concerning them in the De Anima.

Aquinas then procedes to name which works of Aristotle treat which of the grades of life activity:

5. It is necessary therefore that the middle consideration be distinguished in three parts: one of which contains those things which pertain to the living insofar as they are living: and this is contained in the book he writes On Death and Life, in which he also determines about Respiration and Expiration, through which life is preserved in certain living things; and in On Youth and Old Age, into which the states of life are diversified. Similarly, he also takes up what pertains to the living as such in a book entitled On Causes of Length and Shortness of Life, and in a book which he wrote On Health and Sickness which pertains to the disposition of life, and in the book which he is said to have written on On Nutriment and Nourishable, which two books we do not yet have. Other books pertain to the motive part: specifically two books, namely, On the Cause of the Motion of Animals, and On the Progression of Animals in which questions concerning the parts of animals suited for motion are settled. A third [group of books] pertains to the sensitive part concerning which one can consider both that which pertain to the act of the interior or of the exterior sense; and as to this the consideration of the sensitive part is contained in this book, which is entitled On Sense and the Sensed, i.e., on the Sensitive and the Sensible, under which is also contained the treatise On Memory and Reminiscence. And further, it pertains to the consideration of the sensitive part to determine what makes the difference concerning the sense as to what ought to be sensed which he determines through [regarding] sleep and waking in the book entitled On Dream and Waking.

Aristotle in his own introduction to De Sensu does not mention On Nutriment and Nourishable, nor either of the treatises pertaining to animal motion, nor On Dreams. However, there no doubt as to how Aristotle would have situated these three as to grade of life. What is more questionable is whether Aristotle would have grouped those three treatises along with the other middle treatises, for the Movement of Animals ends:

"We have now dealt with the reasons for the parts of each animal, the soul, and also sense-perception, sleep, memory, and general movement. It remains to deal with the generation of animals."(22)

Aristotle's enumeration of the subjects here goes from the object of the most specific treatment, to the object of the most general treatment, to the objects of four middle treatises, ending with an object that receives the most specific sort of treatment. It should noted that this listing is not necessarily meant to indicate the correct grouping of these topics, but possibly only the order in which Aristotle actually covered them. Since generally there is no dependence from the point of view of demonstration of the more specific treatises on the more general ones, the more specific subjects could be examined, albeit not best examined, before the more general ones. Thus from the point of view of determining how Aristotle would divide these treatises, relatively little is to be gained by establishing the historical order in which they were written.(23)

Aquinas, after dividing the middle part of philosophical psychology goes on to state the order in which these subdivisions are best studied:

6. But because it is necessary to go through things which are more similar to things which are dissimilar, such seems to reasonably be the order of the these books, that after the book De Anima in which determinations are made concerning the soul in itself, immediately follows this book about Sense and the Sensed because sensing itself pertains more to the soul than to the body: after which is ordered the book about dreams and waking which implies the binding and loosing of sense. Then follow the books which pertain to the motive power which is rather near to the sensitive part. Lastly, however, are ordered the books which pertain to the common consideration of the living thing, because this consideration chiefly concerns the disposition of the body.

Why doesn't Aquinas base the order of study of these treatises on the principle that one ought to procede from what is more universal to what is less universal? Why does he recommend here that things that are more common to living things, e.g., aging, life and death, be treated later than what is less common, e.g., sleeping and waking?

One might in addition ask from whence comes the principle that one should procede from the more similar to the less, even apart from the question of why Aquinas finds it applicable here. To my knowledge Aristotle never enunciates such a principle.(24) It is not difficult, however, to see that an understanding of one thing that is similar to another is helpful for understanding that other. And as a matter of fact knowledge of the De Anima sometimes facilitates understanding things considered in the middle treatises. For example, in the Movement of Animals Aristotle says: "Now whether soul is moved or not, and if it is moved, how it is moved, has already been discussed in our treatise On Soul. ... it remains to inquire how the soul moves the body and what is the origin of movement in an animal."(25) Now, someone who had grappled with the question of whether the soul is moved is in a better position to inquire into the question of how the soul moves the body for having done so, since the two questions share in common being concerned with motion and the soul. Two other cases where likeness facilitates understanding (the likeness here being in the line of genus and species are): On Sleep where Aristotle relates what he said about the common sense in the DA to the activity of sleeping,(26) and On Dreams where Aristotle relies on what he said about the imagination in DA in order to show what faculty is responsible for dreaming.(27) Thus the questions addressed in the DA are closely related to those found in the middle treatises. And one sees instances of similar continuity between the middle treatises and the final treatises, e.g., a discussion of the brain in the Parts of Animals makes reference back to its role in sleep which was discussed in On Sleep.(28)

Another reason for invoking the principle of going from similar to dissimilar here, and one that arguably Aquinas had in mind, concerns the importance of seeing the continuity of the studies of natural living things. Both for Aristotle and for Aquinas, one of the most fatal errors to be made when studying living things is to think that they are simply the sum total of their parts. One would be more likely to fall into this error, and lose sight of the formal aspect of living things, if after studying the soul in general, one immediately took up the aspects of the living things which are understood to a large extent by looking to the body. Aquinas, following Aristotle, is very aware that a detailed treatment of the parts is liable to lead people in the direction of reductionism. It is not an accident that Aristotle addresses reductionism at great length in the Parts of Animals, but rather it is he feels a need to do so because this treatise considers the material causes of animal activity.(29)

There is a need to determine whether to proceed from common to specific, from vegetative soul to carrot soul with its appropriate body, but there is also a need to determine in what order to proceed amonst the vegetative, motor, and sensitive activities, for these do not stand to each other as universal to particular If one is going to treat these activities at a general level, which to treat first? The sensitive activities shows less material determination and more formal determination, the vegetative vice versa. To facilitate understanding and to avoid the lure of materialism, it is better to start with the sensitive activities.(30)

Let us now finish the commentary:

7. ... He says, therefore, as for the soul in itself, this has already been determined in the De Anima, namely, where he defined the soul. Moreover, he subsequently settled questions concerning the virtues and powers of it: but I say that this [was done] 'from the side of the soul.' For since the powers of the soul, aside from the intellect are the acts of certain parts of the body, they can be considered in two ways: one way according as they pertain to the soul, as certain powers or virtues of it; in another way from the side of the body. Therefore, in the De Anima the powers themselves are determined from the side of the soul itself, but what follows now is to consider animals, and 'all things having life' which he adds on account of plants 'namely, by determining what are the proper operations of them,' that is, of the individual species of animal and plants; 'And those things which are common', namely, to all living things, or to all animals, or to many genera of them. 'Those things therefore which were said about the soul are understood or supposed,' i.e., used themselves in the following works as suppositions that have already been manifested. 'We will speak about the remaining ones, [starting] first from the first' i.e., first about what is common, and afterwards about what is proper. For this is the due order of natural science, as was determined in the beginning of the Physics.

The powers of the soul can be treated insofar as they are powers of the soul, and also from the point of view of the body. DA treats the powers in the former way, but now the consideration is about plants and animals and this cannot be without also considering their bodies. The latter consideration can go on at more general or more specific levels, e.g., one can consider the teeth of carnivores or of dogs, and the more general consideration is more reasonably undertaken first because that way one avoids repetition and also better respects the way our minds naturally work.

Thus, the middle treatises are concerned with many of the same activities as the DA, but regard them more from the point of view of the body, as do the final treatises which which look at them in even more detail. The DA's main concern is first to formulate a general definition of the soul and then to investigate its properties, and subsequently(31) to define the specific types of souls and examine their properties. The principal types of souls are known through the powers of these souls (which in turn are known through their activities, and these in turn through their objects). Thus in the DA the immediate interest in the powers of the soul is so as to determine the types of soul. Once this is accomplished, the powers can be studied in more depth in order to give an understanding of the living things whose powers they are. And in fact as De Koninck points out:

Since the soul is not perfect in itself, to pursue a very complete knowledge of the soul is at the same time to pursue the knowledge of living things in their totality of natural living things.(32)

One might argue that it would be better to subdivide philosophical pyschology in two. One either looks at faculties from the point of view of the soul or from that of the body. When one looks at things from the side of the body, one can do so more generally or more specifically at many levels of generality-specificity, e.g., animal-vertebrate-quadruped-horse-Mustang, and thus one might argue that there is no real reason to designate some of those treatments as intermediary.

It is my thesis that the idea of middle treatises is most justifiable in the case of sense powers, whereas it seems more arbitrary in the case of the vegetative powers. For, while all powers can be studied at a more general or more specific level, e.g., digestion vs. digestion in mammals vs. digestion in mice, some powers are more rooted in the body to start with, e.g., the vegetative powers compared to the senses,(33) and the external senses compared to the internal senses. For this reason even a general consideration of the vegetative powers already involves much reference to the body, whereas this is less so in the case of the sense powers. The DA will point out that unlike non-living matter, a plant can transform foreign material into itself, whence the need to speak of a vegetative soul. However, once one asks a question as to how this transformation takes place, one immediately enters the realms of physiology, chemistry, and physics. In the case of the sensitive soul, on the other hand, there is much one can say about activities proper to it without going into their material aspects. The possibility of doing so can be gathered from a passage in Aristotle:

Hence a physicist would define a passion of soul differently from a dialectician; the latter would define e.g. anger as the appetite for returning pain for pain, or something like that, while the former would define it as a boiling of the blood or warm substance surrounding the heart. The latter assigns the material conditions, the former the form or formulable essence; for what he states is the formulable essence of a fact, though for its actual existence there must be embodiment of it in a material such as is described by the other. Thus the essence of a house is assigned in such a formula as 'a shelter against destruction by wind, rain, and heat'; the physicist would describe it as 'stones, bricks, and timbers'; but there is a third possible description which would say that it was that form in that material with that purpose or end. Which, then, among these is entitled to be regarded as the genuine physicist? The one who confines himself to the material, or the one who restricts hmself to the formulable essence alone? Is it not rather the one who combines both in a single formula?(34)

Aristotle's answer is that the natural philosopher does take interest in both matter and form. Now, of the two, form is more nature than matter.(35) Thus, so long as an understanding of the form is sought without completely disregarding the matter, knowledge of form is knowledge which is more to be desired by the natural philosopher. Now, to the extent that an activity is more formal, more can be said about it with only a vague reference to the body.(36) This is why St. Thomas is able to present a fairly lengthy natural treatment of the passions in the Summa Theologiae. Aquinas does raise questions that have physical implications, for example, whether hope abounds in young people and intoxicated people, (I-II 40.6), and whether sadness is mitigated by crying (I-II 38.2).(37) However, his consideration consists mostly of psychological questions such as whether experience is a cause of hope (I-II 40.5). Now, not all of the powers of the sensible soul are as amenable to so formal an analysis, for some of them are more immersed in matter. As De Koninck points out:

Although the higher powers [such as memory] are conditioned by a more diversified physical structure, one should not be astonished that an abstract study of them has greater latitude and that it already makes us know a lot of things with a great deal of certitude. Indeed the operations, of themselves more disengaged from matter, are in this regard more accessible to abstraction. In contrast, the external senses and the vegetable functions...are more recalcitrant to this abstraction and they demand right away that one designate the organs and that one apply oneself to the study thereof.(38)

Thus, the only type of intermediary treatment that seems possible in the case of the vegetative powers lies in treating them in a more general way as opposed to a less. The senses, especially the internal senses, and the emotions, however, which are less immersed in matter admit of a treatment less abstract than that which is involved in defining the soul and more abstract that that involved in determining the specific material causes which partly account for their activities.

It is worth pointing out here that we are more conscious of our higher life activities than of the lower ones. For example, one is more aware of what reminscence involves than what sight and digestion involve. One is conscious that reminiscing involves tracing steps backwards mentally, whereas one is not conscious of what sight entails beyond the mere awareness of color and seeing, and generally one is virtually or totally oblivious of what goes on in digestion. These latter things are known chiefly through external observation and experience.

Now we are ready to ask whether Aquinas is really basing himself on Aristotle when he divides philosophical psychology into three.

At the very beginning of On Sense and the Sensible Aristotle says that he has already treated the soul "in itself", undoubtedly referring to the DA (which again is not to say that he entirely disregards the body; indeed the soul is defined as the first act of a natural body with organs DA 412b5, #233).

Aristotle then says that he is going on to look at animals, and he pretty much gives a complete list of what Aquinas says falls under the consideration of the middle treatises. In the PA 639a20 Aristotle also names together five of the things Aquinas says are treated by the middle treatises: sleep, respiration, growth, decay, and death. Aristotle groups them together insofar as they are attributes which are same though occurring in different groups. In a number of cases the treatises in question are linked to one another by either an opening or a closing statement, e.g. Length of Life ends by saying: "It remains for us to discuss youth and age, life and death....." Aristotle explicitly says that these treatises examine what pertain to soul and body, rather than what pertains to the soul in itself.

As for those treatises Aquinas ranks third, Aristotle sees PA(39) and Generation of Animals as going together, as can be see from the end of the PA and the also from the beginning of Generation of Animals, the common link being that both bear on the material cause:

With one exception we have now spoken about all the parts that are present in animals, both generally concerning them, and also taking them group by group and dealing separately with the parts peculiar to each, and have shown in what way each part exists on account of the cause which is of a corrsponding kind: I refer to the cause which is 'that for the sake of which' a thing exists. As we know, there are four basic causes... ... And with one exception I have already spoken about all of these causes.... [F]or animals the matter of them is their parts.... Consequently, of the parts it remains to describe those which subserve animals for the purpose of generation, about which I have so far said nothing definite....(40)

The History of Animalsis also to be grouped with PA and the Generation of Animals, for Aristotle says: "I have already described with considerable detail in my Researches upon Animals(41) what and how many are the parts of which the various animals are composed. We must now leave on one side what was said there, as our present task is to consider what are the causes through which each animal is as I there described it."(42)

So Aristotle himself pretty clearly indicates that the treatises are to be grouped into three types, and that the first sort is most formal and the last sort is most material, while the others fall in between as to formality-materiality. Aristotle did not regard this division as being as strict as the division between the three speculative disciplines. In On Sense and the Sensible (c. 4) before he takes up smell and flavor he mentions without apology that he has already discussed sound and voice in DA. Given that the treatises are meant to complement one another, this sort of thing is to be expected.

It does not appear to be the case that Aristotle divides the middle treatises according to the different grades of life, going from the more formal to the less.(43) Aristotle, rather, separates the powers into two groups, one group containing "the most important characteristics of animals" such as sensation, and in the other things which are "common to all things that have a share in life, and others which are peculiar to certain animals."(44) Again, he does not mention the treatises concerning animal motion which Aquinas situates between those concerned with sense and those chiefly concerned with the body.

As to the order of the treatises: Aristotle tells us repeatedly that the proper order to follow is to go from the general to the specific.(45) Within the middle treatises Aristotle says that he is going to begin with what naturally comes first, and he starts with a treatment of sensation despite the fact that sensation is less common than aging. Aristotle apparently thought that it was obvious enough why one ought to proceed in this way, but leaves others the task of making the rationale explicit. Thomas gathered that it is best to go from the similar to the dissimilar. And I in turn gather that one ought to do so because similar issues shed light on each other, and the gradual passage from more formal to the more material helps one avoid the pitfall of reductionism.

Benedict Ashley maintains that Aquinas and Albert are not in accord with Aristotle as to the way of proceeding in philosophical psychology:

The most serious departure from Aristotle's own order is Albert's [and Aquinas's] failure to appreciate (as Averroes did) what is perhaps the best example of Aristotle's method of developing a first principle from a very careful analysis of extensive empirical data, which is to be found in the way Aristotle moves from description and classification in the Historia animalium to theoretical analysis in De partibus animalium to the actual process of forming a real definition which is to serve as a principle of demonstration in De Anima. (46)

What is overlooked here is that the DA requires no extensive empirical data to be understood, but rather it starts from the common experience we all normally acquire without making any special effort to seek it out. We know that cats see us, and dogs whelp if their tails are stepped on, whereas plants show no signs of awareness of the outside world or of emotion, but they do grow. One does not have to take a course in biology to know these things. And these are the sort of things Aristotle starts from when defining the soul.(47)

Before I go on to examine how this division and way of proceeding compares to the way disciplines are divided and pursued nowadays, I would like to point out a somewhat paradoxical tension in the manner of proceeding Aquinas recommends. It is certainly the case that frog is more knowable in itself than amphibian, and amphibian than animal because it is more distinct and more in act. To understand a frog we start by understanding what the soul in general is, and then the animal soul, but since the soul does not have a complete nature we have to study the natural matter with which the soul forms a complete nature.(48) Thus in order to complete our knowledge of living things we have to look more and more at the matter from which they are made. Matter, however, is less nature than form is.(49) Moreover it lacks the intelligibility of form: Thus, in pursuing a distinct knowledge of specific types of living things, one is at the same time pursuing knowledge of what of itself has lesser intelligibility.

The above seems to concord with the fact that in the DA Aristotle speaks of knowledge of the soul as being desirable both because the soul is the most wonderful thing in the world and because knowledge about it is very certain(50) (at least as to that it exists), whereas in the PA he speaks of knowledge about animals as being desirable on account of its certitude and on account of the fact that animals manifest intelligent design.(51) The excellence of a branch of knowledge is determined more by its object than by its certitude. It follows then that the knowledge of natural living things that the lover of wisdom would pursue would be primarily as to their soul which is the act of the body and is more the nature of living things,(52) and then knowledge of those activities where the soul predominates. As to the specific living things' activities and parts, one would seek knowledge of them in order to obtain a more distinct knowledge of some of the specific sorts of living things and to see concrete examples of finality in nature. It does not seem that one would pursue the knowledge of the parts of every type of living thing, given that time is limited, and there are more excellent subjects to study. Yet the fact remains that until the infimae species are known even to the details of their physiology that perfect knowledge of living things is not yet achieved(53)

It would be worthwhile to pursue this matter further, but I must turn now to address briefly the question of how Aquinas's division and recommended course of study measures up against the way studies concerning living things are divided up and the order in which they are pursued nowadays.

For the most part philosophy and science are nowadays regarded as two separate disciplines each with their own way of proceding and overlapping as to subject matter at relatively few points such as the origin of life. This is not the place to embark on an analysis of why this happened. I will limit myself to a few comments as to how this dichotomy affects the way modern commentators examine Aristotle's study of living things. Now, as Arthur Hippler observes: "by and large, the so-called 'psychological treatises' (On the Soul, Sense and the Sensible, Memory and Recollection) were studied completely apart from the 'biological treatises' and vice versa."(54)

Those who endorse this dichotomy often do so on the grounds that the De Anima is mostly devoted to analysing general concepts, whereas treatises such as PA are devoted to matters which are not solved so much by reasoning, as by making specific observations.(55) In DA a dialectical investigation of the opinions of earlier thinkers is very important for arriving at the definition of the soul. Whereas in the PA there are relatively few places when Aristotle mentions the views of others.(56) The PA relies more on focused observation and a limited amount of experiment in order to determine the function of the different parts (resembling to some extent modern science). Thus, there does appear to be reason to differentiate the DA from the PA in terms of conceptual analysis as opposed to empiricism. However, the division conceptual vs. empirical fosters the false notion that philosophy is about ideas detached from experience, whereas science is based on facts devoid of universal understanding. For this reason, the two should rather be distinguished according to the experience each starts from, namely, common experience as opposed to proper experience.

Hippler brings out another complementary reason why modern authors tend to divide the DA, On Sense and the Sensible, On Memory and Reminiscence, against the other treatises, namely, on the grounds that the former treatises are based chiefly on internal experience and thus pertain to psychology, whereas the latter are based chiefly on external experience and thus pertain to biology.(57) I do not intend here to discuss in any detail whether the difference between external and internal experience is sufficient grounds for distinguishing disciplines. However, a few basic points should be kept in mind: First, that sciences are distinguished by their formal object i.e., by the subject matter considered and the way in which it is considered. Secondly, it is one thing to acknowledge a difference in method and use this as a basis for differentiating branches of learning, and it is another to conclude that the branches thus differentiated are thereby entirely dissociated and independent of one another. Astronomy studies mobile bodies by use of mathematics, and yet due to its goal is considered a part of natural philosophy rather than a branch of mathematics.(58)

In the case of the treatises which study living things, whether they start chiefly from internal or from external experience, they are all ordered to the ultimate goal of understanding the various composites of matter and form that have the capacity to move themselves. Indeed, if there is legitimate grounds for subdividing philosophical psychology, one would expect that there be some difference in method, since method has to be adapted to the object of study, which again in the case of the living, is the soul in a certain abstraction, abilities of living things insofar as they are understandable by relating soul to body in a general way, and finally in a much more determinate way, taking in account the the specific bodily make-up of the different sorts of living things.(59) Again many nowadays find the DA's reliance on internal experience adequate reason to completely dissociate it from biology as being non-scientific.

There are other factors which favor the dissociation of DA and the middle treatises from biology, one being the recent growth of biological knowledge which makes it impossible for one person to master all of it, much less have time for questions of a more philosophical nature. (Introductory Cell Biology now fills a large book rather than a single chapter.) And the practical need for specialization in order to survive as a scientist only makes philosophy seem more of a luxury.

As for the middle treatises, the modern disciplines which are the closest to them are psychology and other studies concerning the nature of mind, consciousness, and sensation (Philosophy of Mind, Artificial Intelligence, etc.). There are many interesting research projects being carried on within these areas ranging from the determining the causes behind the formation of false memories to examining the differences in male and female cognitive abilities to understanding the various forms of chemical communication used by animals. Often these sorts of studies ask questions similar to ones that Aristotle asked or would have asked, had he more factual knowledge at his disposal. For example, Aristotle inquired into the causes of good and poor memory,(60) and also sought to understand the importance of the sense of smell in humans as compared to animals.(61)

Despite the similiarity as to interest in modern research and Aristotle's middle treatises, there is a wide divergance as to how to approach the questions, reductionism ruling supreme nowadays. For example, in a single issue of Science & Spirit Magazine (subtitle: Restoring Life's Balance), a magazine devoted to discussing the relation between science and religion we read: "Based on our model ...it seems that all unitary experiences-from watching a beautiful sunset to the most profound states of enlightenment-may have their basis in the flux of our neurotransmitters."(62) "There is no privileged center, no soul, no place where it all comes together--aside from the brain itself. Actually Aristotle's concept of a soul is not bad--the 'vegetative soul' of a plant is not a thing somewhere in the plant; it is simply its homeostatic organization, the proper functioning of its various systems, maintaining the plant's life."(63) "A second sense of 'consciousness' is self-knowledge--the ability to monitor one's own state and reflect back on it. Again, this is child's play for the computational theory: any information processing system can register its own state--for example, you computer probably does a self-check every time you boot it up."(64) "The very crux of the Darwinian explanation of the distinctiveness of humankind is that we are ordered, and thus can function in ways that are not possible for other animals. It is not that we have something different at the substance level, but rather that we are different because of the way that we are put together: by natural selection for adaptive ends."(65) "My understanding of the soul is that it is the almost infinitely complex, dynamic, information-bearing pattern, carried at any instant by the matter of my animated body and continuously developing throughout all the constituent changes of my bodily make-up during the course of my earthly life."(66)

It is a very common problem when scientists turn philosopher (or when philosophers imitate scientists) that they start from the bottom up, with the result that they reject form as any thing other than an end result of the material parts. A case in point is the book Whatever Happened to the Soul?.(67) The blurb says it all:

As science crafts detailed accounts of human nature, what has become of the soul? This collaborative project strives for greater consonance between contemporary science and the Christian faith...Their central theme is a non-dualistic account of the human person that does not consider the 'soul' an entity separable from the body; scientific statements about the physical nature of human being are about exactly the same entity as are theological statements concerning the spiritual nature of human beings.

Another reason which leads modern philosophers and scientists to reject Aristotle's works on living things is the substantial amount of incorrect science contained therein. There is no denying that Aristotle is mistaken on quite a few scientific matters. These errors, as one might expect, are more numerous in those treatises which bear more on the matter, and are relatively few in those which treat the faculties of living things from a more formal perspective. For this reason, scientific inaccuracy are no grounds for dismissing treatises such as De Memoria. It is not always easy to sort out what is good from the treatises more concerned with the matter, and although they do contain the occasional philosophical gem, from the point of view of facts, one is generally better off with a modern biology book. In sorting through Aristotle, it is helpful to understand why so much of his research into the material aspect of living things is flawed. As De Koninck explains:

[Aristotle's] theory concludes at the coincidence between what is most elementary in itself in material things and what is the most elementary for us in our knowledge. And as, in fact, touch is the sense of certitude par excellence, the identification of what is first in things from the point of view of matter with what is moreover the best know by us, as hypothetical as this might be, will not be less tenacious. It will become too reassuring to be put into doubt. And so it was held for a number of centuries. It is understandable why the principle of the primacy of experience in natural science, principle on which Aristotle insists in the treatise where he sets forth the theory of elements, remained so long inoperative in this domain.(68)

As for the PA, the Generation of Animals, and the History of Animals, these treatises correspond roughly with what is treated in biology today. It is the work of another paper to speak of all the likenesses and differences between the two. I will restrict myself to two interrelated points of difference upon which the prooemium, has direct bearing.

The first is that modern biologists tend to lose the forest for the trees, i.e., they fail to see the more general order which is there because they focus too soon or too exclusively on details which fall within this the more general order. An example of this is the inability of most biology students to state what the fundamental difference between a plant and an animal is. Students today will respond that the difference lies in the fact that plant cells have a cell wall whereas animal cells do not. And they are quite satisfied with that as a response. Yet of course they could distinguish plants from animals before they even knew that cells existed, and if they reflected upon their first confused knowledge they would have come up with what is the fundamental difference between the two. However, their mindset is such that they immediately want details, and thus remain ignorant about the natures of the most fundamental division of life forms.

The other classic example of profound ignorance resulting from a failure to consider the more general before the more specific is the inability of most biologists to define life. In fact, it is textbook orthodoxy that it is not possible to define life. This difficulty in part arises once again from zooming in too quickly on detail. To tell that mammalian cells are alive one uses trypan blue; to tell whether yeast cells are alive one uses some other substance. The inability to find a specific test by which one can determine whether or not any given thing is alive is taken as a clear indication that there is no way of knowing what life is.

The other difference between PA and modern biology lies in the latter's reductionist approach.(69) The rejection of the general in favor of the specific coincides with the rejection of what is formal in favor of what is material.

What is a Thomist to do in the face of the divergances between Aquinas's views on living things and those of our contemporaries? If we are going to enter contemporary debates in the areas which treat natural living things there is a need to have a good grasp of what is treated in the DA, and this presupposes knowledge of the Physics. For example, we should be able to recognize Polkinghorne's position above amounts to holding that the soul is a harmony, and we should know the arguments why this cannot be the case. We should be able to define consciousness and self-consciousness. We should be able to explain why mind in the sense of intellect cannot emerge from matter.

There is a need to sort out what is valuable from what is not in the middle treatises, to learn the things of value, and to add to them (for example, to address the question of what is the difference between a reflex and an instinct; and to address what the vis cogitativa is).

There is a need to examine general methodological issues concerning the relation of philosophy and science, an important part of which is determining the different types of experience each start from. We need to learn from Aristotle's mistakes, and to recognize what sort of issues can be solved from common experience and what need special observations and/or experiment. We must defend the role of internal experience, for without it we would not know there was such a thing as life. Aquinas is proposing in the prooemium to De Sensu a single project of understanding living things which is subdivided into parts on the basis of materiality formality which is a different view from those who hold that philosophical psychology and biology are not part of the same enterprise.

We must insist in starting the study of living things from the general and formal end. Otherwise we are liable to be lured along a path that leads to reductionism. A colleague recounts an incident in which he criticized a scientist who was defending the design argument for adopting a reductionist perspective. The scientist answered to the effect that "that's just the way biology is done nowadays, and we have to live with it." Some philosophers, as well, unduly impressed by science, end up abandoning the notion of substantial form or modifying the notion soul in order to fit in with the scientists. Again, we must insist in settling the most general questions first.

Finally, there is a need for the philosopher to be educated in the sense that Aristotle speaks of it in the PA. It is impossible to be an expert in all the different modern fields that treat some aspect of living things. However, we can at least learn the basic principles along with the way of proceeding used in a number of these areas. Then even if we cannot judge everything the scientist says, at least we know where he is coming from and can ask appropriate questions. For example, the kind of understanding of biochemistry that Behe imparts to his reader in Darwin's Black Box is very helpful for understanding modern design debate. The task of acquiring an educational acquaintance in the sciences is made especially difficult by the fact that the methods used nowadays do not always proceed from what is naturally first. It is hard to feel motivated to learn genetics, for example, when one sees right away that geneticists are prone to make certain very general methodological mistakes. However, the firsthand familiarity with the is a trememdous advantage in evaluating the scientists claims.

For myself, I am glad to live in these times where we have wisdom of Aristotle and Aquinas to build on and also a vast amount of accurate scientific knowledge at our disposal. At the same time I feel a healthy fear in the face of the project of trying to piece together a proper understanding of living nature. Hopefully this paper has make some small contribution in preparing the groundwork for such a undertaking.

1. i. In Aristotelis Libros De Sensu et Sensato Commentarium. Ed. Raymundi M. Spiazzi, O.P. (Turin: Marietti, 1949). Hereafter cited as De Sensu.

2. ii. This is exactly what Aristotle says at De Anima 429b22.

3. iii. Cf. De Anima 430b14-17: "And in fact mind as we have described it is what it is by virtue of becoming all things, while there is another which is what it is by virtue of making all things: this is a sort of positive state like light; for in a sense light makes potential colors into actual colors." De Anima, trans. J.A. Smith in The Basic Works of Aristotle, ed. Richard McKeon (New York: Random House, 1968). Hereafter cited as DA.

4. iv. Cf. DA 415a20-II: "But if we are to express what each is, viz. what the thinking power is, or the perceptive, or the nutritive, we must go father back and first give an account of thinking or perceiving, for in the order of investigation the question of what an agent does precedes the question, what enables it to do what it does. If this is correct, we must on the same ground go yet another step farther back and have some clear view of the objects of each; thus we must start with these objects, e.g. with food, with what is perceptible, or with what is intelligible."

5. v. Cf. Metaphysics Bk. VI, c. 1.

6. vi. Cf. DA 413a11: "Since what is certain in itself emerges from what in itself is confused but more observable by us, we must reconsider our results from this point of view."

7. vii. Aquinas, following Porphyr, associates the more universal part of the definition, the genus, with what is material in a thing, although he says explicitly that the genus is not the matter of the thing defined: "The genus is taken from what is material in a thing, the difference indeed from what is formal. As the genus of man is animal, which signifies something having a sensitive nature; which certain stands in a material way to the intellectual nature, from which rational is taken which is the difference of man. For rational indeed signifies something having an intellectual nature. And whence it is that the genus contains the difference in potency, and that the genus and difference stand to one another as matter to form...." In Duodecim Libros Metaphysicorum Aristotelis Expositio, Ed. Raymundi M. Spiazzi, O.P. (Rome: Marietti, 1950), #1697.

8. viii. De Animalibus includes the History of Animals, Parts of Animals, and Generation of Animals.

9. ix. Movement of Animals, trans. E.S. Forster (Cambridge, MA: Harvard University Press, 1968), 698a1-15.

10. x. Charles De Koninck, "Introduction to the Study of the Soul," 38. This introduction prefaces Stanislas Cantin's Précis de psychologie thomiste (Quebec: Laval University, 1948).

11. xi. Cf. DA 407b13-20: "The view we have just been examining, in company with most theories about the soul, involves the following absurdity: they all join the soul to a body, or place it in a body, without adding any specification of the reason of their union, or of the bodily conditions required for it. Yet such explanation can scarcely be omitted; for some community of nature is presupposed by the fact that the one acts and the other is acted upon, the one moves and the other is moved; interaction always implies a special nature in the two things interacting." Aristotle continues for another five lines on this point and returns to it with insistence at 414a20-26.

12. xii. Cf. DA 413b25: "We have no evidence as yet about mind or the power to think; it seems to be a widely different kind of soul, differing as what is eternal from what is perishable; it alone is capable of existence in isolation from all other psychic powers. All the other parts of the soul, it is evident from what we have said, are, in spite of certain statement to the contrary, incapable of separate existence, though, of course, distinguishable by definition."

13. xiii. DA 414b25-34

14. xiv. Charles De Koninck, op. cit., 42.

15. xv. Cf. In Librum Boethii de Trinitate Quaestiones Quinta et Sexta. Ed. Paul Wyser, O.P. (Fribourg: Société Philosophique, 1948) q. V ad 5: "being and substance are said to be separated from matter and motion not through this that it is of the notion of them to exist without matter and motion, as it is of the notion of ass to be without reason, but through this that the notion of them is not in matter and motion, although sometimes they exist in matter and motion, as animal abstracts from rational, although some animal is rational."

16. xvi. Cf. Metaphysics, Bk. VII, cc. 2&3 regarding the need to start the consideration of substance by first examing sensible substance since it is best known.

17. xvii. Thus while Bk. VII and VIII of the Metaphysics deal with sensible substance, it is only in Bk. XIII that immaterial substances is taken up.

18. xviii. Cf. In Octo Libros de Physico Auditu Commentaria. Ed. Angeli M. Pirotta, O.P. (Naples: M. D'Auria Pontificius Editor, 1953), Bk. II, lec. 4, #342.

19. xix. Cf. In Librum Boethii de Trinitate Quaestiones, q. 5, art. 3: "it belongs to man per se that in him is found a rational soul and a body composed from the four elements; whence without these parts man cannot be understood, but it is necessary to put them in his definition, whence they are parts of the species and form. ... For whether it has feet or not, so long as a conjoined thing is put together from a rational soul and a mixed body made from the proper mixture of elements that such a form requires, it will be a man.

20. xx. Cf. DA 429a18-28.

21. xxi. Cf. Metaphysics 1026a5-7: "...it belongs to the physicist to study even some aspects of the soul, so far as it is not independent of matter."

22. xxii. Cf. Movement of Animals 704b1-3.

23. xxiii. In On Youth and Age 468b34 there is a reference to De Partibus. According to Aquinas the best order of study places the De Partibus last. The fact that Aristotle treated these things in reverse order is not particularly problematic since there is no dependence of one on the other from the point of view of demonstration.

24. xxiv. Topics, trans. E.S. Forster (Cambridge, MA: Harvard University Press, 1976), 108b7.

25. xxv. Movement of Animals 700b4-10.

26. xxvi. Cf. On Sleep 455a13-27.

27. xxvii. Cf. On Dreams 459a15-23.

28. xxviii. Cf. Parts of Animals 653a11-21.

29. xxix. Cf. Parts of Animals, trans. A.L. Peck (Cambridge, MA: Harvard University Press, 1968), 640b5-641a14 This discussion continues through 641a33.

"Now those who were the first to study Nature in the early days spent their time in trying to discover what the material principle or the material cause was, and what it was like...In a like manner they describe the formation of animals and plants, saying that the stomach and every kind of receptacle for food and for residue is formed by the water flowing in the body, and the nostril openings are forcibly made by the passage of the breath. Air and water, of course, according to them, are the material of which the body is made: they all say that Nature is composed of substances of this sort. Yet if man and the animals and their parts are products of nature...[i]t is not enough to state simply the substances out of which they are made, as out of fire or out of earth. If we were describing a bed or any other like article, we should endeavor to describe the form of it rather than the matter (bronze, or wood)--or at any rate, the matter, if described would be described as belonging to the concrete whole. For example, a bed is a certain form in certain matter, or; alternatively, certain matter that has a certain form; so we should have to include its shape and the manner of its form in our description of it--because the formal nature is of more fundamental importance than the material nature. ... It must now be evident that the statements of the physiologers are unsatisfactory. We have to state how the animal is characterized, i.e., what is its essence and the character of the animal itself, as well as describing each of its parts; just as with the bed we have to state its form." (Hereafter cited as PA.)

30. xxx. In the DA Aristotle and Aquinas adopts the order opposite to that of the De Sensu, taking up the vegetative powers before the sense powers. I do not find this problematic, first because in the DA the vegetative faculty is being treated in a very general way, so reductionism is not really an issue; and secondly because in this very general treatment there are specific reason to do so, namely: "because this part is first among the other parts in the subjects in which it is found with others: for it is as a foundation of the others, as natural being to which its operations pertain is the foundation of sensible being and intelligible being. And the other reason why it should be treated earlier is because it is common to all living things: for it is separated from the others, but the others are not separated from it, and common things should be taken up prior to other things." In Aristotelis Librum De Anima Commentarium (Italy: Marietti, 1959), #310.

31. xxxi. Cf. DA 415a14: "It is necessary for the students of thse forms of soul first to find a definition of each, expressive of what it is, and then to investigate its derivative properties, and so forth."

32. xxxii. De Koninck, op. cit., 44.

33. xxxiii. Cf. Quaestio Disputata de Anima, q. 13 in which Aquinas points out that the end result of the vegetative powers is not something other than what happens in non-living things as the result of an external agent: "For the generative power is ordered to the end that an individual is produced in being ...the nutritive power is order to the end that it is conserved in being. These things, however, only obtain in inanimate bodies due to extrinsic natural agent."

34. xxxiv. DA 402a29-403b10.

35. xxxv. Cf. Physics 193b8: "The form indeed is 'nature' more than the matter; for a thing is more properly said to be what it is when it has attained to fulfilment than when it exists potentially."

36. xxxvi. De Koninck, op. cit., 41: "This abstraction is possible to the extent that the soul is not entirely immersed in the matter and does not have all its concretion in the body. Without doubt, the knowledge of the formal part will be imperfect to the extent that we are ignorant of the matter, but it will be natural and true when one recognizes the form as being that of a determinate matter, even when we are ignorant what precisely this matter is. It is thus that one can recognize the imagination - the sense by which we know sensible things even in their absence - as a sense faculty and for so much inseparable from a determinate bodily organ without knowing precisely what this organ is. This is why one must say that the present treatise bearing principally on the formal part of natural living things and their operations which we know first by means of internal experience considers the soul 'in a certain abstraction'. Although one cannot abstract from a naturally organized body, one does not yet apply oneself to studying its nature, nor does one seek the structure and particular function of this or that kind of organization."

37. xxxvii. There are a number of works by other authors which are natural as they do go into the physiological factors involved, such as Carol Taveris's Anger and Eva Brann's Imagination ck. The greater portion of these works, however, deal with the psychological aspects of these powers. They also include some considerations that are so detailed, they pass beyond the generality of a middle treatise into the realm a chiefly material consideration.

38. xxxviii. De Koninck, op. cit., 44,45. Cf. also ibid., 46, 47: "We have said that the external senses have their concretion in matter to such a degree that they lend themselves very little to abstract study. Thus, Aristotle has scarcely designated the different kinds of sensible, when he takes up the proper object of sight, immediately defines it, and undertakes explaining the nature of light by means of chemical and physical theories...."

39. xxxix. Cf. PA 697b27: "We have now spoken severally of all the animals: we have described their parts, and stated the reason why each is present in them. Now that this is concluded, the next thing to do is to describe the various ways in which animals are generated."

40. xl. Generation of Animals, trans. A.L. Peck (Cambridge, MA: Harvard University Press, 1963), 715a1-15.

41. xli. Cf. History of Animals 497b5-13. The Researches on Animals is synonymous with the History of Animals.

42. xlii. PA 646a8-12. Cf. Also History of Animals 491a7-12.

43. xliii. Averroes distinguishes the middle treatises according to basically the same principle that of Aquinas does. He says that "In general, in this work he inquires into those faculties which exist in animals insofar as they possess soul. These faculties are of two kinds: first, those that are attributed to the body of an animal by virtue of the existence of the soul in it, as for instance, sense-perception and motion; second, those that are attributed to the soul by virtue of the body." Leaving aside the question of whether or not it make sense to speak of animal faculties which are attributed to the soul by virtue of the body, it is plain enough that, like Thomas, Averroes sees certain faculties as pertaining more to the soul, others more to the body. Unlike Aquinas, however, he does not subdivide the middle treatises into three sorts, and in doing so seems to follow Aristotle's text more closely to the extent Aristotle only names two groups of things (see next note). Averroes, Epitome of Aristotle's Parva Naturalia, trans. Harry Blumberg (Cambridge, MA: The Mediaeval Academy of America), 3.

44. xliv. Aristotle, On Sense and Sensible Objects, trans. W.S. Hett (Cambridge, MA: Harvard University Press, 1975), 436a1-18: Since we have now dealt in detail with the soul by itself, and with each of its several faculties, our next task is to consider animals and all things possessed of life, and to discover what are their peculiar and what are there common activities. All that has already been said about the soul is to be assumed, but let us now discuss the remaining questions, dealing first of all with those which naturally come first. The most important characteristics of animals, whether common or peculiar, are clearly those which belong to both soul and body, such as sensation, memory, passion, desire, and appetite generally, and in addition to these pleasure and pain; for these belong to almost all living creatures. Besides these there are some which are common to all things that have a share in life, and others which are peculiar to certain animals. The most important of these are the four pairs, namely waking and sleep, youth and age, inhalation and exhalation, life and death; we have now to investigate what each of these is, and what are the reasons for their occurrence.

45. xlv. Cf. Physics 184a24; DA 413a12-15; PA 645b1-14.

46. xlvi. Benedict Ashley, "St. Albert and the Nature of Natural Science," in Albertus Magnus and the Sciences, ed. James A. Weisheipl, OP (Toronto: Pontifical Institute of Mediaeval Studies, 1980), 93.

47. xlvii. Cf. DA 404b23 and DA 413a20-30.

48. xlviii. Cf. De Koninck, op. cit., 42.

49. xlix. Cf. Physics 193b8.

50. l. Cf. DA 402a1-4.

51. li. Cf. PA 644b28-645a15.

52. lii. Cf. PA 641a26-33: "...nature is said in two ways: of the matter and of the essence, the latter including the efficient cause and the end. It is of course in the latter sense that the soul or some part of it is nature in regard to the living thing. Hence on this score especially the student of natural science should treat the soul more than the matter, inasmuch as matter is nature more on account of the soul than vice versa. For wood is a bed or a stool because it has the potency to be such."

53. liii. Aristotle appears to be giving a statement of purpose in regard to philosophical psychology in the History of Animals (491a10) when he says that he intends to consider "what differentiates animals and what is common to them all, and to try to discover the causes of these things."

54. liv. Arthur Hippler, op. cit., 7.

55. lv. Cf. Posterior Analytics 88a5: The commensurate universal is precious because it makes clear the cause; so that in the case of facts like these which have a cause other than themselves universal knowledge is more precious than sense-perception and than intuition. ... Hence it is clear that knowledge of things demonstrable cannot be acquired by perception, unless the term perception is applied to the possession of scientific knowledge through demonstration. Nevertheless certain points do arise with regard to connexions to be proved which are referred for their explanation to a failure in sense-perception: there are cases when an act of vision would terminate our inquiry, not because in seeing we should be knowing, but because we should have elicited the universal from seeing; if, for example, we saw the pores in the glass and the light passing through, the reason of the kindling would be clear to us because we should at the same time see it in each instance and intuit that it must be so in all instances. G.R.G. Mure, trans. in The Basic Works of Aristotle, ed. Richard McKeon.

56. lvi. A quick look through the PA turns up 3-4 places where Aristotle refers to others views: at 648a26 he speaks of a dispute concerning heat in animals; at 656a12 he refers to the views of others regarding why the senses are in the head; at 665a31 he disagress with Democritus regarding the presence of viscera in bloodless animals.

57. lvii. Cf. Arthur Hippler, op. cit., 188.

58. lviii. Cf. Physics 193b25-194a11.

59. lix. Another difference in methodology concern the use of theories: DA does not use them, whereas biology sometimes does. The difference in methodology again does not change the fact the two are seeking complementary knowledge of the same subject genus. It is worth noting the methodological difference between the Physics and modern physics, is not so great, as biology sometimes is able to provide an understanding of things independent of theory such as that flooding kills plants because it prevents oxygen from getting to the roots which ordinarily would get there.

60. lx. Cf. On Memory and Reminscence 453a32-b8.

61. lxi. Cf. On Sense and the Sensible 443b30-445a15.

62. lxii. Eugene D'Aquili and Andrew Newberg, "Wired for Ultimate Reality: The Neuropsychology of Religious Experience," in Science and Spirit Magazine, vol. 11, no. 2, May/June 2000, 12.

63. lxiii. Daniel Dennett interviewed by Chris Floyd, in ibid., 19

64. lxiv. Steven Pinker, "Mind at Work: The Computational Consciousness," in ibid., 24.

65. lxv. Michael Ruse, "Darwin on the Brain: Reductionism and Religious Belief," in ibid., 28

66. lxvi. John Polkinghorne quoted in ibid., 29.

67. lxvii. Whatever Happened to the Soul? Scientific and Theological Portraits of Human Nature, eds. Warren S. Brown, Nancey Murphy, and H. Newton Malony, (xx Fortress Press, 1998).

68. lxviii. De Koninck, op. cit., 48.

69. lxix. Cf. Arthur Hippler, op. cit., 102: For modern science, the object of science is to reduce natural things to their ultimate matter. ... For Aristotle, the principle object is the purpose of the material parts for the whole. This is not to suggest that Aristotle is indifferent to matter or material causes; indeed, as the study of the ensouled progresses, it becomes more and more concerned with material causes [organs - tissues - elements]. ... At the same time, one cannot grasp these elemental qualities in the animal until one sees how they make up the flesh, fur and bone; [See Cohen 1989] similarly, one does grasp fully flesh fur and bone until one sees how they are complete in the face, hands and other organs. If an animal is to survive and reproduce, then always and everwhere there are basic organs it will need, and those organs will depend on certain tissues, and so on. The zoologist studies how the tools which the animal has make it suited to the goals of survival and reproduction