Authors/Thomas Aquinas/metaphysics/liber1/lect17

Lecture 17

Latin	English
lib. 1 l. 17 n. 1 Hic improbat positionem Platonis quantum ad hoc, quod ponebat de rerum principiis. Et primo quantum ad hoc quod ponebat principia essendi. Secundo quantum ad hoc quod ponebat principia cognoscendi, ibi, quomodo autem aliquis et cetera. Circa primum ponit sex rationes; quarum prima sumitur ex hoc, quod genera causarum praetermittebat. Unde dicit quod omnino sapientia, scilicet philosophia habet inquirere causas de manifestis, idest de his, quae sensui apparent. Ex hoc enim homines inceperunt philosophari, quod causas inquisiverunt, ut in prooemio dictum est. Platonici autem, quibus se connumerat, rerum principia praetermiserunt, quia nihil dixerunt de causa efficiente, quae est principium transmutationis. Causam vero formalem putaverunt se assignare ponentes ideas. Sed, dum ipsi putaverunt se dicere substantiam eorum, scilicet sensibilium, dixerunt quasdam esse alias substantias separatas ab istis diversas. Modus autem, quo assignabant illa separata esse substantias horum sensibilium, est supervacuus, idest efficaciam non habens nec veritatem. Dicebant enim quod species sunt substantiae eorum inquantum ab istis participantur. Sed hoc quod de participatione dicebant, nihil est, sicut ex supradictis patet. Item species, quas ipsi ponebant, non tangunt causam finalem, quod tamen videmus in aliquibus scientiis, quae demonstrant per causam finalem, et propter quam causam omne agens per intellectum et agens per naturam operatur, ut secundo physicorum ostensum est. Et sicut ponendo species non tangunt causam quae dicitur finis, ita nec causam quae dicitur principium, scilicet efficientem, quae fini quasi opponitur. Sed Platonicis praetermittentibus huiusmodi causas facta sunt naturalia, ac si essent mathematica sine motu, dum principium et finem motus praetermittebant. Unde et dicebant quod mathematica debent tractari non solum propter seipsa, sed aliorum gratia, idest naturalium, inquantum passiones mathematicorum sensibilibus attribuebant.	259. Here Aristotle destroys Plato’s opinion about the principles of things. First, he destroys Plato’s opinion about principles of being; and second (268), his opinion about principles of knowledge (“But how will one”). In regard to the first part he gives six arguments. The first is based on the fact that Plato neglected to deal with the classes of causes. Thus he says that, “in general, wisdom,” or philosophy, has as its aim to investigate the causes “of apparent things,” i.e., things apparent to the senses. For men began to philosophize because they sought for the causes of things, as was stated in the prologue (53). But the Platonists, among whom he includes himself, neglected the principles of things, because they said nothing about the efficient cause, which is the source of change. And by positing the Ideas they thought they had given the formal cause of things. But while they thought that they were speaking of the substance of these things, i.e., sensible ones, they posited the existence of certain other separate substances which differ from these. However, the way in which they assigned these separate substances as the substances of sensible things “is empty talk,” i.e., it proves nothing and is not true. For they said that the Forms are the substances of sensible things inasmuch as they are participated in by sensible things. But what they said about participation is meaningless, as is clear from what was said above (225). Furthermore, the Forms which they posited have no connection with the final cause, although we see that this is a cause in certain sciences which demonstrate by means of the final cause, and that it is by reason of this cause that every intellectual agent and every natural one operates, as has been shown in the Physics, Book II. And just as they do not touch on that cause which is called an end [or goal], when they postulate the existence of the Forms (169), neither do they treat of that cause which is called the source of motion, namely, the efficient cause, which is the opposite, so to speak, of the final cause. But the Platonists by omitting causes of this kind (since they did omit a starting-point and end of motion), have dealt with natural things as if they were objects of mathematics, which lack motion. Hence they said that the objects of mathematics should be studied not only for themselves but for the sake of other things, i.e., natural bodies; inasmuch as they attributed the properties of the objects of mathematics to sensible bodies.
lib. 1 l. 17 n. 2 Deinde cum dicit amplius autem hic ponit secundam rationem, quae talis est. Illud, quod ponitur tamquam rei materia, magis est substantia rei et praedicabile de re, quam illud quod est separatum a re: sed species est separata a rebus sensibilibus: ergo secundum Platonicorum opinionem magis aliquid suscipiet substantiam subiectam, ut materiam, esse substantiam mathematicorum quam speciem separatam. Magis etiam suscipiet eam praedicari de re sensibili quam speciem praedictam. Platonici enim ponebant magnum et parvum esse differentiam substantiae et materiei. Haec enim duo principia ponebant ex parte materiae, sicut naturales ponentes rarum et densum esse primas differentias subiecti idest materiae, per quas scilicet materia transmutabatur, dicentes eas quodammodo scilicet magnum et parvum. Quod ex hoc patet, quia rarum et densum sunt quaedam superabundantia et defectio. Spissum enim est quod habet multum de materia sub eisdem dimensionibus. Rarum quod parum. Et tamen Platonici substantiam rerum sensibilium magis dicebant species quam mathematica, et magis praedicari.	260. Further, one might (134). Here he gives the second argument, which runs thus: that which is posited as the matter of a thing is the substance of a thing, and is predicable of a thing to a greater degree than something which exists apart from it. But a Form exists apart from sensible things. Therefore, according to the opinion of the Platonists, one might suppose that the underlying substance as matter is the substance of the objects of mathematics rather than a separate Form. Furthermore, he admits that it is predicated of a sensible thing rather than the above Form. For the Platonists held that the great and small is a difference of substance or matter; for they referred these two principles to matter, just as the philosophers of nature (115) held that rarity and density are the primary differences of the “underlying subject,” or matter, by which matter is changed, and spoke of them in a sense as the great and small. This is clear from the fact that rarity and density are a kind of excess and defect. For the dense is what contains a great deal of matter under the same dimensions, and the rare is what contains very little matter. Yet the Platonists said that the Forms are the substance of sensible things rather than the objects of mathematics, and that they are predicable of them to a greater degree.
lib. 1 l. 17 n. 3 Deinde cum dicit et de motu hic ponit tertiam rationem, quae talis est. Si ea, quae sunt in sensibilibus, causantur a speciebus separatis, necessarium est dicere quod sit in speciebus idea motus, aut non. Si est ibi aliqua species et idea motus, etiam constat quod non potest esse motus sine eo quod movetur, necesse erit quod species moveantur; quod est contra Platonicorum opinionem, qui ponebant species immobiles. Si autem non sit idea motus, ea autem quae sunt in sensibilibus causantur ab ideis, non erit assignare causam, unde motus veniat ad ista sensibilia. Et sic aufertur tota perscrutatio scientiae naturalis, quae inquirit de rebus mobilibus.	261. And with regard (135). Here he gives the third argument, which runs thus: if those attributes which exist in sensible things are caused by separate Forms, it is necessary to say either that there is an Idea of “motion” among the Forms or there is not. If there is a Form or Idea of motion among the Forms, and there cannot be motion without something that is moved, it also follows that the Forms must be moved. But this is opposed to the Platonists’ opinion, for they claimed that the Forms are immobile. On the other hand, if there is no Idea of motion, and these attributes which exist in sensible things are caused by the Ideas, it will be impossible to assign a cause for the motion which occurs in sensible things; and thus the entire investigation of natural philosophy, which studies mobile things, will be destroyed.
lib. 1 l. 17 n. 4 Deinde cum dicit et quod hic ponit quartam rationem, quae talis est. Si unum esset substantia rerum omnium sicut Platonici posuerunt, oporteret dicere quod omnia sint unum, sicut et naturales, qui ponebant substantiam omnium esse aquam, et sic de elementis aliis. Sed facile est monstrare, quod omnia non sunt unum: ergo positio quae ponit substantiam omnium esse unum, est improbabilis.	262. And what seems easy (136). Then he gives the fourth argument, which runs thus: if unity were the substance of all things, as the Platonists assumed, it would be necessary to say that all things are one, just as the philosophers of nature also did in claiming that the substance of all things is water, and so on for the other elements. But it is easy to show that all things are not one. Hence the position that unity is the substance of all things is not held in high repute.
lib. 1 l. 17 n. 5 Si autem aliquis dicat quod ex positione Platonis non sequitur quod omnia sint unum simpliciter, sed aliquod unum, sicut dicimus aliqua esse unum secundum genus, vel secundum speciem; si quis velit dicere sic omnia esse unum, nec hoc etiam poterit sustineri, nisi hoc quod dico unum, sit genus, vel universale omnium. Per hunc enim modum possemus dicere omnia esse unum specialiter, sicut dicimus hominem et asinum esse animal substantialiter. Hoc autem quibusdam videtur impossibile, scilicet quod sit unum genus omnium; quia oporteret, quod differentia divisiva huius generis non esset una, ut in tertio dicetur, ergo nullo modo potest poni quod substantia rerum omnium sit unum.	263. But let us assume that someone might say that it does not follow, from Plato’s position, that all things are one in an unqualified sense but in a qualified sense, just as we say that some things are one generically or specifically. And if someone wished to say that all things are one in this way, even this could be held only if what I call the one were a genus or universal predicate of all things. For then we could say that all things are one specifically, just as we say that both a man and an ass are animal substantially. But in certain cases it seems impossible that there should be one class of all things, because the difference dividing this class would necessarily not be one, as will be said in Book III (432). Therefore, in no way can it be held that the substance of all things is one.
lib. 1 l. 17 n. 6 Deinde cum dicit nullam namque hic ponit quintam rationem, quae talis est. Plato ponebat post numeros, longitudines et latitudines et soliditates esse substantias rerum sensibilium, ex quibus scilicet corpora componerentur. Hoc autem secundum Platonis positionem nullam rationem habere videtur, quare debeant poni nec in praesenti, nec in futuro. Nec etiam videtur habere aliquam potestatem ad hoc quod sint sensibilium causae. Per praesentia enim hic oportet intelligi immobilia, quia semper eodem modo se habent. Per futura autem corruptibilia et generabilia, quae esse habent post non esse. Quod sic patet. Plato enim ponebat tria genera rerum; scilicet sensibilia, et species, et mathematica quae media sunt. Huiusmodi autem lineae et superficies, ex quibus componuntur corpora sensibilia, non est possibile esse species, quia species sunt numeri essentialiter. Huiusmodi autem sunt post numeros. Nec iterum potest dici quod sunt intermedia inter species et sensibilia. Huiusmodi enim sunt entia mathematica, et a sensibilibus separata: quod non potest dici de illis lineis et superficiebus ex quibus corpora sensibilia componuntur. Nec iterum possunt esse sensibilia. Nam sensibilia sunt corruptibilia; huiusmodi autem incorruptibilia sunt, ut infra probabitur in tertio. Ergo vel ista nihil sunt, vel sunt quartum aliquod genus entium, quod Plato praetermisit.	264. For they do not have (137). Here he gives the fifth argument, which runs thus: Plato placed lengths, widths and solids after numbers as the substances of sensible things, i.e., that of which they are composed. But according to Plato’s position there seems to be no reason why they should be held to exist either now or in the future. Nor does this notion seem to have any efficacy to establish them as the causes of sensible things. For things which exist “now” must mean immobile things (because these always exist in the same way), whereas things which “will exist” must mean those which are capable of generation and corruption, which acquire being after non-being. This becomes clear thus: Plato posited three classes of things—sensible things, the Forms and the objects of mathematics, which are an intermediate class. But such lines and surfaces as those of which sensible bodies are composed cannot be Forms; for the Forms are essentially numbers, whereas such things [i.e., the lines and surfaces composing bodies] come after numbers. Nor can such lines and surfaces be said to be an intermediate class between the Forms and sensible things; for the things in this intermediate class are the objects of mathematics, and exist apart from sensible things; but this cannot be said of the lines and surfaces of which sensible bodies are composed. Nor again can such lines and surfaces be sensible things; for the latter are corruptible, whereas these lines and surfaces are incorruptible, as will be proved below in Book III (466). Therefore these things are either nothing at all or they constitute a fourth class of things, which Plato omitted.
lib. 1 l. 17 n. 7 Deinde cum dicit et omnino hic ponit sextam rationem, quae talis est. Impossibile est invenire principia alicuius multipliciter dicti, nisi multiplicitas dividatur. Ea enim quae solo nomine convenientia sunt et differunt ratione, non possunt habere principia communia, quia sic haberent rationem eamdem, cum rei cuiuscumque ratio ex suis principiis sumatur. Distincta autem principia his, quibus solum nomen commune est, assignari impossibile est, nisi his quorum principia sunt assignanda adinvicem diversis. Cum igitur ens multipliciter dicatur et non univoce de substantia et aliis generibus, inconvenienter assignat Plato principia existentium, non dividendo abinvicem entia.	265. And, in general (138). Here he gives the sixth argument, which runs thus: it is impossible to discover the principles of anything that is spoken of in many senses, unless these many senses are distinguished. Now those things which agree in name only and differ in their intelligible structure cannot have common principles; otherwise they would have the same intelligible structure, since the intelligible structure of a thing is derived from its own principles. But it is impossible to assign distinct principles for those things which have only the name in common, unless it be those whose principles must be indicated to differ from each other. Therefore, since being is predicated both of substance and the other genera in different senses and not in the same sense, Plato assigned inadequate principles for things by failing to distinguish beings from each other.
lib. 1 l. 17 n. 8 Sed quia aliquis posset aliquibus ratione differentibus, quibus nomen commune est, principia assignare, singulis propria principia captando, sine hoc quod nominis communis multiplicitatem distingueret, hoc etiam Platonici non fecerunt. Unde et aliter, idest alia ratione inconvenienter rerum principia assignaverunt quaerentes ex quibus elementis sunt entia, secundum hunc modum, quo quaesierunt, ut scilicet non omnibus entibus sufficientia principia assignarent. Non enim ex eorum dictis est accipere ex quibus principiis est agere aut pati, aut curvum aut rectum, aut alia huiusmodi accidentia. Assignabant enim solum principia substantiarum, accidentia praetermittentes.	266. But since someone could assign principles to things which differ in their intelligible structure and have a common name, by adjusting proper principles to each without distinguishing the many senses of the common name, and since the Platonists have not done this, then “in another way,” i.e., by another argument, they assigned inadequate principles to things when they looked for the elements of which things are made, i.e., in the way in which they sought for them, inasmuch as they did not assign principles which are sufficient for all things. For from their statements it is impossible to understand the principles of which either action and passion, curvature and straightness, or other such accidents, are composed. For they only indicated the principles of substances and neglected accidents.
lib. 1 l. 17 n. 9 Sed si aliquis defendendo Platonem dicere vellet, quod tunc contingit omnium entium elementa esse acquisita aut inventa, quando contingit solarum substantiarum principia habita esse vel inventa, hoc opinari non est verum. Nam licet principia substantiarum etiam quodammodo sint principia accidentium, tamen accidentia propria principia habent. Nec sunt omnibus modis omnium generum eadem principia, ut ostendetur infra, undecimo vel duodecimo huius.	267. But if in defense of Plato someone wished to say that it is possible for the elements of all things to have been acquired or discovered at the moment when the principles of substances alone happen to have been acquired or discovered, this opinion would not be true. For even if the principles of substances are also in a sense the principles of accidents, nevertheless accidents have their own principles. Nor are the principles of all genera the same in all respects, as will be shown below in Book XI (2173) and Book XII (2455) of this work.
lib. 1 l. 17 n. 10 Deinde cum dicit quomodo autem disputat contra Platonem quantum ad hoc, quod ponebat ideas esse principia scientiae in nobis. Et ponit quatuor rationes: quarum prima est. Si ex ipsis ideis scientia in nobis causatur, non continget addiscere rerum principia. Constat autem quod addiscimus. Ergo ex ipsis ideis scientia non causatur in nobis. Quod autem non contingeret aliquid addiscere sic probat. Nullus enim praecognoscit illud quod addiscere debet; sicut geometra, etsi praecognoscat alia quae sunt necessaria ad demonstrandum, tamen ea quae debet addiscere non debet praecognoscere. Et similiter est in aliis scientiis. Sed si ideae sunt causa scientiae in nobis, oportet quod omnium scientiam habeant, quia ideae sunt rationes omnium scibilium: ergo non possumus aliquid addiscere, nisi aliquis dicatur addiscere illud quod prius praecognovit. Unde si ponatur quod aliquis addiscat, oportet quod non praeexistat cognoscens illa quae addiscit, sed quaedam alia cum quibus fiat disciplinatus, idest addiscens praecognita omnia, idest universalia aut quaedam, idest singularia. Universalia quidem, sicut in his quae addiscuntur per demonstrationem et definitionem; nam oportet sicut in demonstrationibus, ita in definitionibus esse praecognita ea, ex quibus definitiones fiunt, quae sunt universalia; singularia vero oportet esse praecognita in his quae discuntur per inductionem.	268. But how will one (139). Here he argues dialectically against Plato’s position that the Ideas are the principles of our scientific knowledge. He gives four arguments, of which the first is this: if our scientific knowledge is caused by the Ideas themselves, it is impossible for us to acquire knowledge of the principles of things. But it is evident that we do acquire knowledge. Therefore our knowledge is not caused by the Ideas themselves. That it would be impossible to acquire knowledge of anything, he proves thus: no one has any prior knowledge of that object of which he ought to acquire knowledge; for example, even though in the case of geometry one has prior knowledge of other things which are necessary for demonstration, nevertheless the objects of which he ought to acquire knowledge he must not know beforehand. The same thing is also true in the case of the other sciences. But if the Ideas are the cause of our knowledge, men must have knowledge of all things, because the Ideas are the intelligible structures of all knowable things. Therefore we cannot acquire knowledge of anything) unless one might be said to acquire knowledge of something, which he already knew. if it is held, then, that someone acquires knowledge, he must not have any prior knowledge of the thing which he comes to know, but only of certain other things through which he becomes instructed; i.e., one acquires knowledge through things previously known, [either] “all,” i.e., universals, “or some of them,” i.e.,:singular things. One learns through universals in the case of those things which are discovered by demonstration and definition, for in the case of demonstrations and definitions the things of which definitions or universals are composed must be known first. And in the case of things which are discovered by induction singular things must be known first.
lib. 1 l. 17 n. 11 Deinde cum dicit sed si est hic ponit secundam rationem, quae talis est. Si ideae sunt causa scientiae, oportet nostram scientiam esse nobis connaturalem. Sensibilia enim per haec naturam propriam adipiscuntur, quia ideas participant secundum Platonicos. Sed potissima disciplina sive cognitio est illa quae est nobis connaturalis, nec eius possumus oblivisci, sicut patet in cognitione primorum principiorum demonstrationis, quae nullus ignorat: ergo nullo modo possumus omnium scientiam ab ideis in nobis causatam oblivisci. Quod est contra Platonicos, qui dicebant quod anima ex unione ad corpus obliviscitur scientiae, quam naturaliter in omnibus habet: et postea per disciplinam addiscit homo illud quod est prius notum, quasi addiscere nihil sit nisi reminisci.	269. But if this, science (140). Here he gives the second argument, which runs thus: if the Ideas are the cause of our knowledge, it must be connatural to us; for men grasp sensible things through this proper nature, because sensible things participate in Ideas according to the Platonists. But the most important knowledge or science is one that is connatural to us and which we cannot forget, as is evident of our knowledge of the first principles of demonstration, of which no one is ignorant. Hence there is no way in which we can forget the knowledge of all things caused in us by the Ideas. But this is contrary to the Platonists’ opinion, who said that the soul as a result of its union with the body forgets the knowledge which it has of all things by nature, and that by teaching a man acquires knowledge of something that he previously knew, as though the process of acquiring knowledge were merely one of remembering.
lib. 1 l. 17 n. 12 Deinde cum dicit amplius autem hic ponit tertiam rationem, quae talis est. Ad rerum cognitionem requiritur, quod homo non solum cognoscat formas rerum, sed etiam principia materialia, ex quibus componitur. Quod ex hoc patet, quia de his interdum contingit esse dubitationem, sicut de hac syllaba sma, quidam dubitant utrum sit composita ex tribus literis scilicet s, m, a, aut sit una litera praeter omnes praedictas habens proprium sonum. Sed ex ideis non possunt cognosci nisi principia formalia, quia ideae sunt formae rerum: ergo non sunt sufficientes causae cognitionis rerum principiis materialibus remanentibus ignotis.	270. Again, how is anyone (141). Here he gives the third argument, which runs thus: in order to know things a man must acquire knowledge not only of the forms of things but also of the material principles of which they are composed. This is evident from the fact that occasionally questions arise regarding these; for example, with regard to this syllable sma, some raise the question whether it is composed of the three letters s, m and a, or whether it is one letter which is distinct from these and has its own sound. But only the formal principles of things can be known through the Ideas, because the Ideas are the forms of things. Hence the Ideas are not a sufficient cause of our knowledge of things when material principles remain unknown.
lib. 1 l. 17 n. 13 Deinde cum dicit amplius autem hic ponit quartam rationem, quae talis est. Ad cognitionem rerum oportet de sensibilibus notitiam habere, quia sensibilia sunt manifesta elementa materialia omnium rerum, ex quibus componuntur, sicut voces compositae, ut syllabae et dictiones componuntur ex propriis elementis. Si igitur per ideas scientia in nobis causatur, oportet quod per ideas causetur in nobis cognitio sensibilium. Cognitio autem in nobis causata ex ideis sine sensu est accepta, quia per sensum non habemus habitudinem ad ideas. In cognoscendo ergo sequitur quod aliquis non habens sensum possit cognoscere sensibilia, quod patet esse falsum. Nam caecus natus non potest habere scientiam de coloribus.	271. Again, how could (142). Here he gives the fourth argument, which runs thus: in order to know reality we must know sensible things, because sensible things are the apparent material element of which all things are composed, just as complex sounds (such as syllables and words) are composed of their proper elements. If, then, knowledge is caused in us by the Ideas, our knowledge of sensible things must be caused by the Ideas. But the knowledge which is caused in us by the Ideas is grasped without the senses, because we have no connection with the Ideas through the senses. Therefore in the act of perception it follows that anyone who does not have a sense can apprehend the object of that sense. This is clearly false; for a man born blind cannot have any knowledge of colors.
lib. 1 l. 17 n. 14 Deinde cum dicit quoniam ergo hic colligit ea, quae ab antiquis de principiis dicta sunt; dicens quod ex prius dictis est manifestum, quod antiqui philosophi conati sunt quaerere causas a nobis in libro physicorum determinatas, et quod per dicta eorum non habemus aliquam causam extra causas ibi declaratas. Has autem causas obscure dixerunt, et quodammodo omnes ab eis sunt tactae, quodammodo vero nullam earum tetigerunt. Sicut enim pueri de novo loqui incipientes imperfecte et balbutiendo loquuntur, ita philosophia priorum philosophorum nova existens, visa est balbutiendo et imperfecte de omnibus loqui circa principia. Quod in hoc patet quod Empedocles primo dixit quod ossa habent quamdam rationem idest commixtionem proportionis, quae quidem ratio est quod quid est et substantia rei. Sed similiter necessarium est de carne et de singulis aliorum, aut de nullo. Omnia enim ista ex elementis commixta sunt. Et propter hoc patet quod caro et os et omnia huiusmodi non sunt id quod sunt, propter materiam quae ab eo ponitur quatuor elementa, sed propter hoc principium, scilicet formale. Hoc autem Empedocles quasi ex necessitate veritatis coactus posuit aliquo alio expressius ista dicente, sed ipse manifeste non expressit. Et sicut expresse non manifestaverunt naturam formae, ita nec materiae, ut supra de Anaxagora dictum est. Et similiter nec alicuius alterius principii. De talibus ergo quae ab aliis imperfecte dicta sunt, dictum est prius. Iterum autem in tertio libro recapitulabimus de istis quaecumque circa hoc potest aliquis dubitare ad unam partem vel ad aliam. Ex talibus enim dubitationibus forsitan investigabimus aliquid utile ad dubitationes, quas posterius per totam scientiam prosequi et determinare oportet.	272. From the foregoing (143). Here he summarizes the statements made by the ancient philosophers. He says that from what has been said above it is evident that the ancient philosophers attempted to investigate the cause which he [Aristotle] dealt with in the Physics, and that in their statements we find no cause in addition to those established in that work. However, these men discussed these causes obscurely; and while in a sense they have mentioned all of these causes, in another sense they have not mentioned any of them. For just as young children at first speak imperfectly and in a stammering way, in a similar fashion this philosophy, since it was new, seems to speak imperfectly and in a stammering way about the principles of all things. This is borne out by the fact that Empedocles was the first to say that bones have a certain ratio, or proportional mixture [of the elements], and that this is a thing’s quiddity or substance. But the same thing must also be true of flesh and of every other single thing or of none of them, for all of these things are mixtures of the elements. And for this reason it is evident that flesh and bone and all things of this kind are not what they are because of their matter, which he identified with the four elements, but because of this principle-their form. However, Empedocles, compelled as it were by the need for truth, would have maintained this view if it had been expressed more clearly by someone else, but he did not express it clearly. And just as the ancient philosophers have not clearly expressed the nature of form, neither have they clearly expressed the nature of matter, as was said above about Anaxagoras (90). Nor have they clearly expressed the nature of any other principles. Therefore, concerning such thing, as have been stated imperfectly, we have spoken of this before (190). And with regard to these matters we will restate again in Book III (423) whatever difficulties can be raised on both sides of the question. For perhaps from such difficulties we will discover some useful information for dealing with the problems which must be examined and solved later on throughout this whole science. </tbody>