[10] And what is thought to be easy—to show that all things are one—is not done; for by ‘exposition’ all things do not come to be one but there comes to be a One-in-itself, if we grant all the assumptions. And not even this follows, if we do not grant that the universal is a class; and this in some cases it cannot be.
Nor can it be explained either how the lines and planes and solids that come [15] after the numbers exist or can exist, or what meaning they have; for these can neither be Forms (for they are not numbers), nor the intermediates (for those are the objects of mathematics), nor the perishable things. This is evidently a distinct fourth class.
In general, if we search for the elements of existing things without distinguishing the many senses in which things are said to exist, we cannot succeed, especially [20] if the search for the elements of which things are made is conducted in this manner. For it is surely impossible to discover what acting or being acted on, or the straight, is made of, but if elements can be discovered at all, it is only the elements of substances; therefore to seek the elements of all existing things or to think one has them is incorrect. And how could we learn the elements of all things? Evidently we cannot start by knowing something before. For as he who is learning geometry, [25] though he may know other things before, knows none of the things with which the science deals and about which he is to learn, so is it in all other cases. Therefore if there is a science of all things, as some maintain, he who is learning this will know [30] nothing before. Yet all learning is by means of premises which are (either all or some of them) known before,—whether the learning be by demonstration or by definitions; for the elements of the definition must be known before and be familiar; and learning by induction proceeds similarly. But again, if the science is innate, it is [993a1] wonderful that we are unaware of our possession of the greatest of sciences. Again, how is one to know what all things are made of, and how is this to be made evident? This also affords a difficulty; for there might be a conflict of opinion, as there is about certain syllables; some say za is made out of s and d and a, while others say it [5] is a distinct sound and none of those that are familiar. Further, how could we know the objects of sense without having the sense in question? Yet we should, if the elements of which all things consist, as complex sounds consist of their proper elements, are the same. [10]
10 · It is evident, then, even from what we have said before, that all men seem to seek the causes named in the Physics, and that we cannot name any beyond these; but they seek these vaguely; and though in a sense they have all been described before, in a sense they have not been described at all. For the earliest [15] philosophy is, on all subjects, like one who lisps, since in its beginnings it is but a child. For even Empedocles says bone exists by virtue of the ratio in it. Now this is the essence and the substance of the thing. But it is similarly necessary that the ratio should be the substance of flesh and of everything else, or of none; there it is on [20] account of this that flesh and bone and everything else will exist, and not on account of the matter, which he names,—fire and earth and water and air. But while he would necessarily have agreed if another had said this, he has not said it clearly.
On such questions our views have been expressed before; but let us return to enumerate the difficulties that might be raised on these same points; for perhaps we [25] may get some help towards our later difficulties.
BOOK II (a)
1 · The investigation of the truth is in one way hard, in another easy. An indication of this is found in the fact that no one is able to attain the truth adequately, while, on the other hand, no one fails entirely, but every one says [993b1] something true about the nature of things, and while individually they contribute little or nothing to the truth, by the union of all a considerable amount is amassed. [5] Therefore, since the truth seems to be like the proverbial door, which no one can fail to hit, in this way it is easy, but the fact that we can have a whole truth and not the particular part we aim at shows the difficulty of it.
Perhaps, as difficulties are of two kinds, the cause of the present difficulty is [10] not in the facts but in us. For as the eyes of bats are to the blaze of day, so is the reason in our soul to the things which are by nature most evident of all.
It is just that we should be grateful, not only to those whose opinions we may share, but also to those who have expressed more superficial views; for these also contributed something, by developing before us the powers of thought. It is true that [15] if there had been no Timotheus we should have been without much of our lyric poetry; but if there had been no Phrynis there would have been no Timotheus. The same holds good of those who have expressed views about the truth; for from the better thinkers we have inherited certain opinions, while the others have been responsible for the appearance of the better thinkers.
[20] It is right also that philosophy should be called knowledge of the truth. For the end of theoretical knowledge is truth, while that of practical knowledge is action (for even if they consider how things are, practical men do not study what is eternal but what stands in some relation at some time). Now we do not know a truth without its cause; and a thing has a quality in a higher degree than other things if in [25] virtue of it the similar quality belongs to the other things (e.g. fire is the hottest of things; for it is the cause of the heat of all other things); so that that which causes derivative truths to be true is most true. Therefore the principles of eternal things must be always most true; for they are not merely sometimes true, nor is there any cause of their being, but they themselves are the cause of the being of other things, [30] so that as each thing is in respect of being, so is it in respect of truth.
[994a1] 2 · Evidently there is a first principle, and the causes of things are neither an infinite series nor infinitely various in kind. For, on the one hand, one thing cannot proceed from another, as from matter, ad infinitum, e.g. flesh from earth, earth from air, air from fire, and so on without stopping; nor on the other hand can the [5] efficient causes form an endless series, man for instance being acted on by air, air by the sun, the sun by Strife, and so on without limit. Similarly the final causes cannot go on ad infinitum,—walking for the sake of health, this for the sake of happiness, [10] happiness for the sake of something else, and so one thing always for the sake of another. And the case of the formal cause is similar. For in the case of an intermediate, which has a last term and a prior term outside it, the prior must be the cause of the later terms. For if we had to say which of the three is the cause, we should say the first; surely not the last, for the final term is the cause of none; nor [15] even the intermediate, for it is the cause only of one. It makes no difference whether there is one intermediate or more, nor whether they are infinite or finite in number. But of series which are infinite in this way, and of the infinite in general, all the parts down to that now present are alike intermediates; so that if there is no first there is no cause at all.
[20] Nor can there be an infinite process downwards, with a beginning in the upper direction, so that water should proceed from fire, earth from water, and so always some other kind should be produced. For one thing comes from another in two ways (if we exclude the sense in which ‘from’ means ‘after’, as we say ‘from the Isthmian games come the Olympian’), (a) as the man comes from the boy, by the boy’s [25] changing, or (b) as air comes from water. By ‘as the man comes from the boy’ we mean ‘as that which has come to be from that which is coming to be, or as that which is finished from that which is being achieved’ (for as becoming is between being and not being, so that which is becoming is always between that which is and that which is not; and the learner is a man of science in the making, and this is what is meant when we say that from a learner a man of science is being made); on the [30] other hand, coming from another thing as water comes from air implies the destruction of the other thing. This is why changes of the former kind are not reversible,—the boy does not come from the man (for what comes to be from the process of coming to be is no
t what is coming to be but what exists after the process [994b1] of coming to be; for it is thus that the day comes from the morning—in the sense that it comes after the morning; and therefore the morning cannot come from the day); but changes of the other kind are reversible. But in both cases it is impossible that the number of terms should be infinite. For terms of the former kind being intermediates must have an end, and terms of the latter kind change into one [5] another; for the destruction of either is the generation of the other.
At the same time it is impossible that the first cause, being eternal, should be destroyed; for while the process of becoming is not infinite in the upward direction, a first cause by whose destruction something came to be could not be eternal.
Further, the final cause is an end, and that sort of end which is not for the sake of something else, but for whose sake everything else is; so that if there is to be a last [10] term of this sort, the process will not be infinite; but if there is no such term there will be no final cause. But those who maintain the infinite series destroy the good without knowing it. Yet no one would try to do anything if he were not going to come to a limit. Nor would there be reason in the world; the reasonable man, at least, always acts for a purpose; and this is a limit, for the end is a limit. [15]
But the formal cause, also, cannot be referred always to another definition which is fuller in expression. For the original definition is always more of a definition, and not the later one; and in a series in which the first term is not correct, the next is not so either.—Further, those who speak thus destroy knowledge; for it is [20] not possible to have this till one comes to what is indivisible. And knowledge becomes impossible; for how can one think things that are infinite in this way? For this is not like the case of the line, to whose divisibility there is no stop, but which we cannot think of if we do not make a stop; so that one who is tracing the infinitely divisible line cannot be counting the possibilities of section. [25]
But further, the matter in a changeable thing must be cognized.1
Again, nothing infinite can exist; and if it could, at least being infinite is not infinite.
But if the kinds of causes had been infinite in number, then also knowledge would have been impossible; for we think we know, only when we have ascertained [30] the causes, but that which is infinite by addition cannot be gone through in a finite time.
3 · The effect which lectures produce on a hearer depends on his habits; for [995a1] we demand the language we are accustomed to, and that which is different from this seems not in keeping but somewhat unintelligible and foreign because it is not customary. For the customary is more intelligible. The force of custom is shown by the laws, in whose case, with regard to the legendary and childish elements in them, [5] habit has more influence than our knowledge about them. Some people do not listen to a speaker unless he speaks mathematically, others unless he gives instances, while others expect him to cite a poet as witness. And some want to have everything done accurately, while others are annoyed by accuracy, either because they cannot [10] follow the connexion of thought or because they regard it as pettifoggery. For accuracy has something of this character, so that as in trade so in argument some people think it mean. Therefore one must be already trained to know how to take each sort of argument, since it is absurd to seek at the same time knowledge and the way of attaining knowledge; and neither is easy to get.
[15] The minute accuracy of mathematics is not to be demanded in all cases, but only in the case of things which have no matter. Therefore its method is not that of natural science; for presumably all nature has matter. Hence we must inquire first what nature is: for thus we shall also see what natural science treats of [and whether it belongs to one science or to more to investigate the causes and the principles of [20] things].2
BOOK III (B)
1 · We must, with a view to the science which we are seeking, first recount [25] the subjects that should be first discussed. These include both the other opinions that some have held on certain points, and any points besides these that happen to have been overlooked. For those who wish to get clear of difficulties it is advantageous to state the difficulties well; for the subsequent free play of thought implies the solution of the previous difficulties, and it is not possible to untie a knot [30] which one does not know. But the difficulty of our thinking points to a knot in the object; for in so far as our thought is in difficulties, it is in like case with those who are tied up; for in either case it is impossible to go forward. Therefore one should have surveyed all the difficulties beforehand, both for the reasons we have stated [35] and because people who inquire without first stating the difficulties are like those who do not know where they have to go; besides, a man does not otherwise know even whether he has found what he is looking for or not; for the end is not clear to [995b1] such a man, while to him who has first discussed the difficulties it is clear. Further, he who has heard all the contending arguments, as if they were the parties to a case, must be in a better position for judging.
The first problem concerns the subject which we discussed in our prefatory [5] remarks. It is this—whether the investigation of the causes belongs to one or to more sciences, and, if to one, whether this should survey only the first principles of substance, or also the principles on which all men base their proofs, e.g. whether it is possible at the same time to assert and deny one and the same thing or not, and all [10] other such questions. And if the science in question deals with substance, whether does one science deal with all substances, or more than one, and if more, whether are all akin, or must some of them be called forms of wisdom and the others something else? And this itself is also one of the things that must be discussed—whether sensible substances alone should be said to exist or others also besides [15] them, and whether these others are of one kind or there are several classes of substances, as is supposed by those who believe both in Forms and in mathematical objects intermediate between these and sensible things. We must inquire, then, as we say, into these questions, and also whether our investigation is concerned only with substances or also with the essential attributes of substances. Further, with [20] regard to the same and other and like and unlike and contrariety, and with regard to prior and posterior and all other such terms, about which the dialecticians try to inquire, starting their investigation from reputable premises only,—whose business is it to inquire into all these? Further, we must discuss the essential attributes of [25] these themselves; and we must ask not only what each of these is, but also whether one thing always has one contrary. Again, whether the principles and elements of things are the classes, or the parts present in each thing into which it is divided; and if they are the classes, whether they are the classes that are predicated proximately of the individuals, or the highest classes, e.g. whether animal or man is the first [30] principle and the more independent of the individual instance? And we must inquire and discuss especially whether there is, besides the matter, any thing that is a cause in itself or not, and whether this can exist apart or not, and whether it is one or more in number. Once more, is there something apart from the concrete thing (by the concrete thing I mean the matter with something predicated of it), or is [35] there nothing apart, or is there something in some cases though not in others, and what sort of cases are these? Again we ask whether the principles are limited in [996a1] number or in kind, both those in the formulae and those in the substratum; and whether the principles of perishable and of imperishable things are the same or different; and whether they are all imperishable or those of perishable things are perishable. Further, there is the question which is hardest of all and most [5] perplexing, whether unity and being, as the Pythagoreans and Plato said, are not attributes of something else but are the substance of existing things, or this is not the case, but the substratum is something else,—as Empedocles says, love; as someone else says, fire; while one says water and one air. Again we ask whether the [10] principles are universal or like individual things, and whether they ex
ist potentially or actually; further, whether they are potential or actual in any other sense than in reference to movement; for these questions also would present much difficulty. Further, whether numbers and lines and figures and points are a kind of substance [15] or not, and if they are substances whether they are separate from sensible things or present in them? With regard to all these matters not only is it hard to get possession of the truth, but it is not easy even to think out the difficulties well.
2 · First then with regard to what we mentioned first, does it belong to one or to more sciences to investigate all the kinds of causes? How could it belong to one [20] science to know the principles if these are not contrary?
Further, there are many things to which not all the principles pertain. For how can a principle of change or the nature of the good be present in unchangeable things, since everything that in itself and by its own nature is good is an end, and a [25] cause in the sense that for its sake the other things both come to be and are, and since an end or purpose is the end of some action, and all actions imply change; so that in unchangeable things this principle could not exist nor could there be a good-in-itself. This is why in mathematics nothing is proved by means of this kind of [30] cause, nor is there any demonstration of this kind—‘because it is better, or worse’; indeed no one even mentions anything of the kind. And so for this reason some of the Sophists, e.g. Aristippus, ridiculed mathematics; for in the arts, even in handicrafts, e.g. in carpentry and cobbling, the reason always given is ‘because it is better, or worse’, but the mathematical sciences take no account of goods and evils.
The Complete Works of Aristotle Page 269