In libros Aristotelis De caelo et mundo expositio On the Heavens Liber 1 Book 1 Prooemium Introduction De ordine huius libri ad alios scientiae naturalis libros. Eius materia et subiectum Subject matter of this book and its relation to the subject matter of natural science in general 1. Sicut Philosophus dicit in I Physic., tunc opinamur cognoscere unumquodque, cum causas cognoscimus primas, et principia prima, et usque ad elementa. Ex quo manifeste philosophus ostendit in scientiis esse processum ordinatum, prout proceditur a primis causis et principiis usque ad proximas causas, quae sunt elementa constituentia essentiam rei. Et hoc est rationabile: nam processus scientiarum est opus rationis, cuius proprium est ordinare; unde in omni opere rationis ordo aliquis invenitur, secundum quem proceditur ab uno in aliud. Et hoc patet tam in ratione practica, cuius consideratio est circa ea quae nos facimus, quam in ratione speculativa, cuius consideratio est circa ea quae sunt aliunde facta. 1. As the Philosopher says in Physics I, we judge that we know a thing when we know the first causes and the first. principles down to the elements. Plainly from this the Philosopher shows that in sciences there is an orderly process, a procedure from first causes and principles to the proximate causes, which are the elements constituting the essence of a thing. And this is reasonable: For the method pursued in sciences is a work of reason, whose prerogative it is to establish order; wherefore, in every work of reason is found some order according to which one goes from one thing to another. And this shows up not only in the practical reason, which considers things that we make, but in the speculative reason as well, which considers things made by some other source. 2. Invenitur autem processus de priori ad posterius in consideratione practicae rationis secundum quadruplicem ordinem: 2. The process from prior to subsequent is found in the act of the practical reason with respect to a fourfold order: primo quidem secundum ordinem apprehensionis, prout artifex primo apprehendit formam domus absolute, et postea inducit eam in materiam; first, according to the order of apprehension, inasmuch as an artisan first apprehends the form of a house absolutely and then realizes it in matter; secundo secundum ordinem intentionis, secundum quod artifex intendit totam domum perficere, et propter hoc facit quidquid operatur circa partes domus; secondly, according to the order of intention, inasmuch as an artisan intends to complete the house and for that purpose does whatever he does to the parts of the house; tertio secundum ordinem compositionis, prout scilicet prius dolat lapides, et postea compingit eos in unum parietem; thirdly, according to the order of combining, inasmuch as he first trims the stones and then joins them into one wall; quarto secundum ordinem sustentationis artificii, prout artifex primo iacit fundamentum, super quod ceterae partes domus sustentantur. fourthly, according to the order of supporting the edifice, inasmuch as the artisan first lays the foundation, upon which the other parts of the house are supported. Similiter etiam invenitur quadruplex ordo in consideratione rationis speculativae. In like manner, a fourfold order is found in the consideration of speculative reason. Primus quidem secundum quod proceditur a communibus ad minus communia. Et hic ordo respondet proportionaliter primo ordini, quem diximus apprehensionis: universalia enim considerantur secundum formam absolutam, particularia vero secundum applicationem formae ad materiam; sicut Philosophus in I De caelo dicit quod qui dicit caelum, dicit formam, qui autem dicit hoc caelum, dicit formam in materia. First, because there is a process from the general to the less general. And this order corresponds to the first order which we have called the order of apprehension, for universals are considered according to an absolute form, but particulars by applying form to matter, as the Philosopher in On the Heavens says, that the word "heaven" signifies a form, and "this heaven" signifies a form in matter. Secundus ordo est secundum quod proceditur a toto ad partes. Et hic ordo proportionaliter respondet ordini quem diximus intentionis, prout scilicet totum est prius in consideratione quam partes, non qualescumque, sed partes quae sunt secundum materiam et quae sunt individui; sicut semicirculus, in cuius definitione ponitur circulus (est enim semicirculus media pars circuli), et acutus angulus, in cuius definitione ponitur rectus (est enim acutus angulus minor recto). Accidit autem circulo et recto angulo sic dividi: unde huiusmodi non sunt partes speciei. Huiusmodi enim partes sunt priores in consideratione quam totum, et ponuntur in definitione totius, sicut carnes et ossa in definitione hominis, ut dicitur in VII Metaphys. The second order is that according to which one goes from the whole to the parts. And this corresponds to the order of intention, inasmuch as, namely, the whole is considered prior to the parts, not just any parts but parts which are according to matter and which are of the individual—as in the case of a semi-circle, in the definition of which "circle" is used (for it is "half a circle") and of an acute angle, in the definition of which "right angle" is used (for an acute angle is an angle "less than a right angle"). To be divided in that manner is incidental to a circle and to a right angle; hence, neither is a part of the species of a circle or right angle. For parts of this sort [i.e. parts of the species] are prior in consideration to the whole and are used in the definition of the whole, as are flesh and bones in the definition of man, as is said in Metaphysics VII. Tertius autem ordo est secundum quod proceditur a simplicibus ad composita, inquantum composita cognoscuntur per simplicia, sicut per sua principia. Et hic ordo comparatur tertio ordini, quem diximus compositionis. The third order is that according to which one goes from the simple to the combined, inasmuch as composites are known in terms of the simple, as through their principles. And this order is compared to the third order, which is the order of combining. Quartus autem ordo est secundum quod principales partes necesse est prius considerare, sicut cor et hepar quam arterias et sanguinem. Et hic proportionatur practico ordini, secundum quod fundamentum prius iacitur. But the fourth order is the one that calls for the principal parts to be considered first, as are the heart and liver before the arteries and blood. And this corresponds in the practical order to that order according to which the foundation is laid first. 3. Et hic quadruplex ordo consideratur etiam in processu scientiae naturalis. 3. This fourfold order is also considered in the procedure of natural science. Nam primo determinantur communia naturae in libro Physicorum, in quo agitur de mobili inquantum est mobile. Unde restat in aliis libris scientiae naturalis huiusmodi communia applicare ad propria subiecta. Subiectum autem motus est magnitudo et corpus: quia nihil movetur nisi quantum. For, first of all, things common to nature are determined in the book of the Physics, in which mobile being is treated insofar as it is mobile. Hence what remains in the other books of natural science is to apply these common things to their proper subjects. The subject of motion, however, is a magnitude and body, because nothing is moved except what is quantified. In corporibus autem est attendere tres alios ordines: uno quidem modo secundum quod totum universum corporeum est prius in consideratione quam partes eius; alio modo secundum quod simplicia corpora prius considerantur quam mixta; tertio secundum quod inter simplicia corpora prius necesse est de priori considerare, scilicet de caelesti corpore, per quod omnia alia firmantur. Et haec tria in hoc libro aguntur, qui apud Graecos intitulatur De caelo. Now it is in bodies that the three other orders are considered: in one way, insofar as the entire corporeal universe is prior in consideration to its parts; in another way, insofar as simple bodies are considered before the mixed; thirdly, insofar as, among the simple bodies, the first must be considered first, i.e., the heavenly body, through which all the others are sustained. And these three are treated in this book, which the Greeks entitle On the Heavens. Traduntur enim in hoc libro quaedam pertinentia ad totum universum, sicut patet in primo libro; For in this book are treated certain things that pertain to the entire universe, as is plain in book I; quaedam pertinentia ad corpus caeleste, sicut patet in secundo; and things that pertain to the heavenly body, as is plain in book II; quaedam pertinentia ad alia simplicia corpora, sicut patet in tertio et quarto. and things that pertain to the simple bodies, as is plain in books III-IV. Et ideo rationabiliter hic liber ordinatur primus post librum Physicorum. Et propter hoc statim in principio huius libri agitur de corpore, cui necesse est applicari omnia quae tradita sunt de motu in libro Physicorum. Consequently, it is with good reason that this book is first in order after the book of the Physics. For this reason the first topic of discussion in the very beginning of this book is body, to which must be applied all that was set forth about motion in the Physics. 4. Quia igitur diversa in hoc libro traduntur, dubium fuit apud antiquos expositores Aristotelis de subiecto huius libri. Alexander enim opinatus est quod subiectum de quo principaliter in hoc libro agitur, sit ipsum universum. Unde, cum caelum tripliciter dicatur, quandoque ipsa ultima sphaera, quandoque totum corpus quod circulariter movetur, quandoque autem ipsum universum, asserit hunc librum intitulari De caelo, quasi De universo vel De mundo: in cuius assertionem assumit quod philosophus in hoc libro determinat quaedam ad totum universum pertinentia, puta quod sit finitum, quod sit unum tantum, et alia huiusmodi. 4. Because diverse things are treated in this book, there was among the early expositors of Aristotle a question about the subject of this book. For Alexander believed that the subject principally treated herein is the universe. Hence, since "the heavens" is subject to a threefold meaning—for sometimes it refers to the outermost sphere, sometimes to the whole body moved circularly, and sometimes to the entire universe—he asserts that this book is entitled On the Heavens as though meaning On the Universe or On the World. In asserting this he assumes that the Philosopher is here determining certain matters pertaining to the entire universe, for example, that it is finite, that it is unique, and things of this sort. E contrario autem aliis videtur quod subiectum de quo principaliter in hoc libro intenditur, est corpus caeleste quod circulariter movetur; et propter hoc intitulatur De caelo. De aliis autem corporibus determinatur in hoc libro vel ex consequenti, inquantum continentur a caelo et eius influentiam recipiunt, sicut Iamblichus dixit; vel per accidens, inquantum aliorum corporum notitia assumitur ad manifestandum ea quae dicuntur de caelo, ut dixit Syrianus. Sed hoc non videtur probabile: quia postquam philosophus in secundo libro determinavit de caelo, in tertio et quarto subiungit considerationem de aliis simplicibus corporibus, quasi principaliter de eis intendens. Non enim consuevit philosophus principalem partem alicuius scientiae assignare his quae per accidens assumuntur. On the other hand, it seems to some that the main subject handled in this book is the heavenly body which is moved circularly, for which reason it is entitled On the Heavens. Other bodies, however, are discussed therein consequentially, insofar as they are contained by the heavens and influenced by them, as Iamblichus said; or only incidentally, insofar as a knowledge of other bodies is assumed in order to explain what is being said of the heavens, as Syrianus says. But this does not seem probable, for after the Philosopher has finished his discussion of the heavens in book II, he treats in books III and IV of the other simple bodies as though they were his main subject. Now the Philosopher is not wont to assign a principal part in some science to things that are brought up only incidentally. Et ideo aliis visum est, sicut Simplicius dixit, quod intentio philosophi in hoc libro est determinare de simplicibus corporibus, inquantum conveniunt in communi intentione simplicis corporis: et quia inter simplicia corpora principalius est caelum, a quo alia dependent, ideo denominatur totus liber a caelo. Et, sicut dicit, non obstat quod in hoc libro determinantur quaedam quae pertinent ad totum universum: quia huiusmodi conditiones conveniunt universo inquantum conveniunt caelesti corpori, scilicet esse finitum et sempiternum, et alia huiusmodi. Si autem intentio principalis philosophi esset determinare de universo, sive de mundo, oporteret quod Aristoteles considerationem suam extenderet ad omnes partes mundi, etiam usque ad plantas et animalia, sicut Plato in Timaeo. Sed eadem ratione possumus arguere contra Simplicium: quia si in hoc libro principaliter intenderet de corporibus simplicibus, oporteret quod omnia quae pertinent ad corpora simplicia in hoc libro traderentur; nunc autem in hoc libro traduntur solum ea quae pertinent ad levitatem et gravitatem ipsorum, alia vero traduntur in libro De generatione. Therefore it seemed to others, as Simplicius said, that the intention of Aristotle in this book is to determine about simple bodies inasmuch as they share in the common notion of simple body; and because among simple bodies, the chief is the heavens, on which the others depend, the entire book gets its name from the heavens. And, so he says, it makes no difference that in this book things pertaining to the whole universe are considered, for the conditions in question belong to the universe insofar as they belong to the heavenly body, i.e., to be finite and eternal, and so on. But if the principal intention of the Philosopher were to determine about the universe or the world, then he would have had to extend his consideration to all the parts of the world, even down to plants and animals, as Plato does in the Timaeus. But the same argument could be used against Simplicius, because if Aristotle in this book intended to treat principally of the simple bodies, then in this book he would have had to mention everything that pertains to the simple bodies, whereas he discusses only what pertains to their lightness and heaviness, while he treats the other aspects in the book On Generation. 5. Et ideo rationabilior videtur sententia Alexandri, quod subiectum huius libri sit ipsum universum, quod dicitur "caelum" vel "mundus"; et quod de simplicibus corporibus determinatur in hoc libro, secundum quod sunt partes universi. Constituitur autem universum corporeum ex suis partibus secundum ordinem situs: et ideo de illis solum partibus universi determinatur in hoc libro, quae primo et per se habent situm in universo, scilicet de corporibus simplicibus. Unde et de quatuor elementis non determinatur in hoc libro secundum quod sunt calida vel frigida, vel aliquid huiusmodi; sed solum secundum gravitatem et levitatem, ex quibus determinatur eis situs in universo. Aliis autem partibus universi, puta lapidibus, plantis et animalibus, non determinatur situs secundum se, sed secundum simplicia corpora: et ideo de his non erat in hoc libro agendum. Et hoc consonat ei quod consuevit apud Latinos dici, quod in hoc libro agitur de corpore mobili ad situm, sive secundum locum: qui quidem motus communis est omnibus partibus universi. 5. Accordingly, the opinion of Alexander appears more reasonable, i.e., that the subject of this book is the universe itself, which is called "the heavens" or "the world," and that determination is made concerning simple bodies in this book accordingly as they are parts of the universe. Now, the corporeal universe is composed of its parts according to an order of position; consequently this book determines only concerning those parts of the universe that primarily and per se have position in the universe, namely, the simple bodies. That is why the four elements are not dealt with in this book from the aspect of their being hot or cold or something of that sort, but only with respect to their heaviness and lightness, from which their position in the universe is determined. Other parts of the universe, such as stones, plants, and animals, have a determined place in the universe not according to what they are in themselves but according to the simple bodies; consequently, they are not treated in this book. And this agrees with what is usually said among the Latins, that this book discusses body that is mobile with respect to position or place, such motion being common to all the parts of the universe. Lectio 1 Lecture 1 De quibus ad scientiam naturalem pertineat determinare The things it pertains to natural science to consider De natura scientia fere plurima videtur circa corpora et magnitudines et horum existens passiones et motus, adhuc autem circa principia quaecumque talis substantiae sunt. Natura enim constantium haec quidem sunt corpora et magnitudines; haec autem habent corpus et magnitudinem; haec autem principia habentium sunt. 1 The science which has to do with nature clearly concerns itself for the most part with bodies and magnitudes and their properties and movements, but also with the principles of this sort of substance, as many as they may be. For of things constituted by nature some are bodies and magnitudes, some possess body and magnitude, and some are principles of things which possess these. 6. Quia igitur in hoc libro primo incipit applicare Aristoteles ad corpora, ea quae communiter dicta sunt de motu in libro Physicorum, 6. In this first book Aristotle begins for the first time to apply to bodies the things that were said about motion in a general way in the book of the Physics. ideo primo prooemialiter ostendit quod ad scientiam naturalem pertinet determinare de corporibus et magnitudinibus; For that reason he first shows by way of introduction that it pertains to natural science to determine about bodies and magnitudes; secundo incipit prosequi suum propositum, ibi: continuum quidem et cetera. second he begins to carry out his proposal, at now a continuum [Lecture 2]. Circa primum ponit talem rationem. Res naturales sunt corpora et magnitudines, et quae ad haec pertinent: sed scientia naturalis est de rebus naturalibus: ergo scientia naturalis consistit circa corpora et magnitudines. With respect to the first he presents this argument: natural things are bodies and magnitudes and whatever pertains to these. But natural science is about natural things. Therefore, natural science consists in treating of bodies and magnitudes. 7. Primo ergo ponit conclusionem, dicens quod scientia quae est de natura, fere plurima, idest in maiori parte, videtur esse existens circa corpora et magnitudines, idest lineas et superficies. De quibus tamen aliter considerat naturalis quam geometra. Naturalis quidem considerat de corporibus inquantum sunt mobilia, de superficiebus autem et lineis inquantum sunt termini corporum mobilium: geometra autem considerat de eis prout sunt quaedam quanta mensurabilia. Et quia ad scientiam pertinet non solum considerare subiecta, sed etiam passiones, ut dicitur in I Poster., ideo subiungit quod naturalis scientia existit circa praedictorum passiones et motus: ut per passiones intelligantur alterationes et alii motus consequentes, secundum quos alteratur aliquid in substantia rei: subdit autem et motus, quasi procedens a speciali ad commune. Vel per motus intelligit specialiter motus locales, qui sunt perfectiores in genere motuum. Vel per passiones intelligit proprietates, per motus autem operationes rerum naturalium, quae non sunt sine motu. Et quia in qualibet scientia oportet considerare principia, subiungit quod naturalis scientia est circa quaecumque principia praedictae substantiae; scilicet corporeae mobilis. Per quod datur intelligi quod ad naturalem pertinet praecipue considerare de corpore inquantum est in genere substantiae, sic enim est subiectum motus: ad geometram autem inquantum est in genere quantitatis, sic enim mensuratur. 7. First [1] therefore, he posits the conclusion, saying that the science which treats of nature seems to be for the most part concerned with bodies and magnitudes, i.e., lines and surfaces. However, the natural philosopher considers these in a different way from the geometer. For the former treats of bodies insofar as they are mobile, and of surfaces and lines insofar as they are the boundaries of mobile bodies; the geometer, on the other hand, considers them insofar as they are measurable quantities. And because a science should consider not only subjects but also their passions, as is said in Post. Anal. I, he therefore adds that natural science is concerned with the passions and motions of the aforesaid—by passions meaning alterations and other consequent motions, with respect to which something is altered in the substance of a thing; and he adds, and motions, as though going from the particular to the general. Or perhaps by motions he specifically understands local motions, which are the more perfect in the genera of motions. Or by passions is meant the properties, and by motions the operations of natural things, which do not occur without motion. And because in every science principles must be considered, he adds that natural science is concerned with any and all the principles of the afore-mentioned substance, namely, mobile corporeal substance. By this we are given to understand that it pertains to natural science primarily to consider body insofar as it is in the genus of substance, for it is in this respect that it is the subject of motion; whereas it pertains to the geometer to consider it insofar as it is in the genus of quantity, for thus it is measured. Et quia minor est manifesta, scilicet quod scientia naturalis sit de rebus naturalibus, subiungit maiorem, dicens quod ideo scientia naturalis existit circa praedicta, quia eorum quae sunt secundum naturam, quaedam sunt corpora et magnitudines, sicut lapides et alia inanimata; quaedam habent corpus et magnitudinem, sicut plantae et animalia, quorum principalior pars est anima (unde magis sunt id quod sunt secundum animam quam secundum corpus); quaedam vero sunt principia habentium corpus et magnitudinem, sicut anima, et universaliter forma, et materia. Et ex hoc apparet quare dixit quod scientia de natura fere plurima existit circa corpora et magnitudines: quaedam enim pars eius est circa habentia corpus et magnitudines; est etiam circa principia horum; est etiam circa quaedam quae non sunt in natura, quae aliqui attribuerunt corporibus et magnitudinibus, scilicet circa vacuum et infinitum. Since the minor premise is plain, namely, that natural science is concerned with natural things, he adds the major, saying that the reason why natural science is concerned with the aforementioned is that among things which are according to nature, some are bodies and magnitudes, e.g., stones and other inanimate things; and some have body and magnitude, as do plants and animals, whose principal part is the soul (hence they are what they are more with respect to soul than with respect to body); finally, some things are principles of things having body and magnitude—for example, the soul, and universally form, and matter. From this is clear why he said that the science of nature is for the most part concerned with bodies and magnitudes: for one part of this science is concerned with things having body and magnitude; it is also concerned with the principles of these; it is further concerned with some things which do not exist in nature but which some have attributed to bodies and magnitudes, namely, the void and the infinite.