Commentary Aristotle Physics
Commentary on Aristotle’s Physics
Book 1. The Principles of Natural Things
Lecture 1. The matter and subject of physics
Since, indeed, to understand and to know happen in all sciences of which there are principles, causes, or elements, it is through acquaintance with these that knowledge is attained. For we do not think that we know a thing until we know its first causes and first principles and have carried our analysis as far as its elements. Plainly, therefore, in the science of nature, as in other branches of study, our first task will be to try to determine what relates to its principles.
The natural way of doing this is to start from the things that are more knowable and certain to us and proceed toward those that are clearer and more knowable by nature; for the same things are not “knowable relatively to us” and “knowable” without qualification.
So, in the present inquiry, we must follow this method and advance from what is more obscure by nature but clearer to us toward what is more clear and more knowable by nature.
Now, what is plain and obvious to us at first is confused masses, the elements and principles of which become known to us later by analysis. Thus we must advance from universals to singulars.
For it is a whole that is best known to sense perception, and a universal is a kind of whole, comprehending many things within it, like parts.
Much the same thing happens in the relation of the name to the formula. A name, such as “round,” means vaguely a sort of whole: its definition divides into particular elements.
Similarly, children begin by calling all men “father” and all women “mother,” but later on distinguish each of them.
1. Because this book upon which we intend to comment here, the Physics, is the first book of natural science, it is necessary in the beginning to decide what is the matter and the subject of natural science.
Since every science is in the intellect, it should be understood that something is rendered intelligible in act insofar as it is in some way abstracted from matter. And, inasmuch as things are differently related to matter, they pertain to different sciences.
Furthermore, since every science is established through demonstration, and since the definition is the middle term in a demonstration, it is necessary that sciences be distinguished according to the diverse modes of definition.
2. It must be understood, therefore, that there are some things whose existence depends upon matter and that cannot be defined without matter. Further, there are other things that, even though they cannot exist except in sensible matter, have no sensible matter in their definitions. And these differ from each other as the curved differs from the snub. For the snub exists in sensible matter and sensible matter must fall in its definition, for the snub is a curved nose. And the same is true of all natural things, such as man and stone. But sensible matter does not fall in the definition of the curved, even though the curved cannot exist except in sensible matter. And this is true of all the mathematical objects, such as numbers, magnitudes, and figures.
There are still other things that do not depend upon matter, either according to their existence or according to their definitions. And this is either because they never exist in matter, such as God and the other separated substances, or because they do not universally exist in matter, such as substance, potency and act, and being itself.
3. Now metaphysics deals with things of this latter sort, while mathematics deals with those things that depend upon sensible matter for their existence but not for their definition. And natural science, which is called “physics,” deals with those things that depend upon matter not only for their existence but also for their definition.
And because everything that has matter is mobile, it follows that mobile being is the subject of natural philosophy. For natural philosophy is about natural things, and natural things are those whose principle is nature. But nature is a principle of motion and rest in that in which it is. Therefore, natural science deals with those things that have in them a principle of motion.
4. Furthermore, those things that follow from something common must be treated first and by themselves. Otherwise, it becomes necessary to repeat such things many times while discussing each instance of that which is common.
Therefore, it was necessary that one book in natural science be set forth in which those things that are consequent upon mobile being in common are treated, just as first philosophy, in which those things that are common to being insofar as it is being are determined, is set forth for all the sciences.
This, then, is the book, the Physics, or On Physics or of the Natural to be Heard, because it was handed down to hearers by way of instruction. And its subject is mobile being simply.
I do not, however, say “mobile body,” because the fact that every mobile being is a body is proven in this book, and no science proves its own subject. Thus, in the very beginning of the De caelo, which follows this book, we begin with the notion of body.
Moreover, after the Physics, there are other books of natural science in which the species of motion are treated: in De caelo, we treat the mobile according to local motion, which is the first species of motion; in De generatione, we treat of motion’s relation to form and of the first mobile things, the elements, with respect to their changes in general; but we consider their particular changes in Meteororum, and in De mineralibus, we consider the mobile mixed bodies that are non-living. Living bodies are considered in De anima and the books that follow it.
5. To this book, then, the Philosopher writes a preface in which he shows the order in which natural science must proceed. In this preface, he does two things.
First, he shows that it is necessary to begin with a consideration of principles.
Second, at “the natural way of doing this” (184a16; [6]), he shows that, among principles, it is necessary to begin with the more universal principles.
Therefore, he first gives the following argument. In all sciences of which there are principles, causes, or elements (184a10), understanding and science proceed from a knowledge of the principles, causes, and elements. Now, the science that is about nature has principles, elements, and causes. Therefore, in that science it is necessary to begin with a determination of principles.
When he says, to understand, he refers to definitions, and when he says, to know, he refers to demonstrations. For as demonstrations are from causes, so also are definitions, since a complete definition is a demonstration differing only by position, as is said in Posterior Analytics 1.8.
When he speaks of principles or causes or elements, however, he does not intend to signify the same thing by each. For “cause” is wider in meaning than “element.” An element is a first component of a thing and is in the composed thing, as is said in Metaphysics 5. Thus, letters are elements of speech, but syllables are not. But those things are called “causes” upon which things depend for their existence or their coming to be.
Thus, even that which is outside the thing or that which is in it—though the thing is not first composed of it—can be called a “cause,” though it cannot be called an “element.” But “principle” implies a certain order in any progression. Thus, something can be a principle that is not a cause, as that from which motion begins is a principle of motion but is not a cause, and a point is a principle of a line but not a cause.
Therefore, by principle he seems to mean moving causes and agents in which—more than in others—there is found an order of some progression. By causes he seems to mean formal and final causes upon which things most of all depend for their existence and their coming to be. By elements he means properly the first material causes.
Moreover, he uses these terms disjunctively and not conjunctively in order to point out that not every science demonstrates through all the causes. For mathematics demonstrates only through the formal cause. Metaphysics demonstrates principally through the formal and final causes, but also through the agent. Natural science, however, demonstrates through all the causes.
He then proves the first proposition of his argument from common opinion. This is also proven in Posterior Analytics 1.2. For a man thinks that he knows something when he knows all its causes from the first to the last. The meanings here of causes, principles, and elements is exactly the same as we have explained above, even though the Commentator disagrees.
Furthermore, Aristotle says, as far as its elements, because matter is the last to be known. For matter is for the sake of form, and form is from the agent for the sake of the end, unless it itself is the end. For example, we say that a saw has teeth in order to cut, and these teeth ought to be made of iron so they will be apt for cutting.
6. Next, at “the natural way of doing this” (184a16), he shows that, among principles, it is necessary to treat the more universal ones first.
And first, he shows this by means of an argument;
second, by an example, at “for it is a whole” (184a23; [9]).
Therefore, he first gives the following argument. It is natural for us to proceed in knowing from those things that are better known to us to those that are better known by nature. But the things that are better known to us are confused, and such are the universals. Therefore, it is necessary for us to proceed from universals to singulars.
7. To clarify the first proposition, he makes the point that things that are better known to us and things that are better known according to nature are not the same. Rather, those things better known according to nature are less known to us. And, because the natural way or order of learning is that we should come to what is unknown to us from what is known to us, it is necessary for us to arrive at the better known by nature from the better known to us.
It must be noted, however, that “what is known by nature” and “what is known simply” are the same. Those things are better known simply that are in themselves better known. But those things are better known in themselves that have more being, because each thing is knowable insofar as it is a being. However, those beings are greater that are greater in act. Thus, these are the most knowable by nature.
For us, however, the converse is true, because we proceed in understanding from potency to act. Our knowledge begins from sensible things, which are material and intelligible in potency. Thus, these things are known by us before the separated substances, which are better known according to nature, as is clear in Metaphysics 2.
Therefore, he does not say knowable by nature as if nature knew these things, but because they are known better in themselves and according to their proper natures. And he says better known and more certain because, in the sciences, not just any kind of knowledge is sought, but certain knowledge.
Next, in order to understand the second proposition, it must be known that those things are here called confused that contain in themselves something potential and indistinct. And because knowing something indistinctly is a mean between pure potency and perfect act, therefore, while our intellect proceeds from potency to act, it knows the confused before it knows the distinct. But it has complete science in act when it arrives, through resolution, at a distinct knowledge of the principles and elements. And this is the reason why the confused is known by us before the distinct.
That universals are confused is clear. For universals contain in themselves their species in potency, and whoever knows something in the universal knows it indistinctly. The knowledge, however, becomes distinct when each of the things contained in potency in the universal is known in act. For he who knows “animal” does not know “rational” except in potency. But knowing something in potency is prior to knowing it in act. Therefore, according to this order of learning, in which we proceed from potency to act, we know “animal” before we know “man.”
8. It would seem, however, that this is contrary to what the Philosopher says in Posterior Analytics 1.2, that singulars are better known to us, whereas universals are better known by nature or simply.
But it must be understood that, there, he takes as singulars the individual sensible things themselves, which are better known to us because the knowledge of sense, which is of singulars, does precede in us the knowledge of the intellect, which is of universals. But because intellectual knowledge is more perfect, and because universals are intelligible in act—whereas singulars are not (since they are material)—universals are better known simply and according to nature.
Here, however, by singulars, he means not the individuals themselves, but the species. And these are better known by nature, existing more perfectly, as it were, and being known with a distinct knowledge. But the genera are known by us first, being known, as it were, confusedly and in potency.
It should be known, however, that the Commentator explains this passage in another way. At the natural way of doing this (184a16), he says that the Philosopher wishes to explain the method of demonstration of this science:
this science demonstrates through the effect and what is posterior according to nature. Hence, what is said here is to be understood of the progression in demonstration, and not of the progression in determination.
Then, at “now, what is plain and obvious” (184a21), according to the Commentator, Aristotle intends to make clear what things are better known to us and what is better known by nature, namely, what is composed of simple things—understanding confused to mean composed.
Finally, then, he concludes, as if to a corollary, that we must proceed from the more universal to the less universal.
It is clear that the Commentator’s explanation is not suitable, because he does not join the whole passage to one intention. Moreover, the Philosopher does not intend to set forth the mode of demonstration of this science here, because he will do this in book 2, according to his order of treatment. Furthermore, the “confused” should not be taken to mean “composed,” but rather to mean “indistinct.” For nothing could be concluded from such universals, because genera are not composed of species.
9. Next, at “for it is a whole” (184a23), he clarifies his position with three examples.
The first of these is taken from the integral sensible whole. He says that, since the sensible whole is better known to the sense, the intelligible whole is also better known to the intellect. But the universal is a sort of intelligible whole, because it comprehends many as parts—namely, its inferiors. Therefore, the universal is known better to us intellectually.
But it would seem that this proof is not effective, because he uses whole, part, and comprehension equivocally.
However, it must be said that the integral whole and the universal agree in that each is confused and indistinct. For just as he who apprehends a genus does not apprehend the species distinctly, but in potency only, so also he who apprehends a house does not yet distinguish its parts. Hence it is that a whole is first known to us as confused. This applies to both of these wholes. However, to be composed is not common to each whole. Thus, it is clear that Aristotle significantly said confused above, and not composed.
10. Next, at “much the same thing” (184a26), he gives another example taken from the integral intelligible whole. For that which is defined is related to the things defining it as a kind of integral whole, insofar as the things defining it are in act in that which is defined.
But he who apprehends a name—for example, man or circle—does not at once distinguish the defining principles. Thus it is that the name is, as it were, a sort of whole and is indistinct, while the definition divides into particular elements, that is, distinctly sets forth the principles of that which is defined.
This, however, seems to be contrary to what he said above. For the things that define would seem to be more universal, and these, he said, were first known by us. Furthermore, if that which is defined were better known to us than the things that define, we would not grasp that which is defined through the definition, for we grasp nothing except through that which is better known to us.
But it must be said that the things that define are in themselves known to us before that which is defined, but we know the thing that is defined before we know that these are the things that define it. Thus we know animal and rational before we know man. But man is known confusedly before we know that animal and rational are the things that define man.
11. Next, at “similarly, a child” (184b12), he gives the third example taken from the more universal sensible. For as the more universal intelligible is first known to us intellectually—for example, animal is known before man—so the more common sensible is first known to us according to sense—for example, we know this is an animal before we know this is a man.
And I say “first according to sense” both with reference to place and with reference to time. This is true according to place, for when someone is seen at a distance, we perceive him to be a body before we perceive that he is an animal, and an animal before we perceive him to be a man, and finally we perceive that he is Socrates. And in the same way, with reference to time, a boy apprehends this individual as some man before he apprehends this man, Plato, who is his father. And this is what he says, children begin by calling all men “father” and all women “mother,” but later on distinguish; that is, they know each determinately.
From this, it is clearly shown that we know a thing confusedly before we know it distinctly.