Dist. 13, Art. 3, Q. 1
Book II: On the Creation of Things · Distinction 13
## ARTICULUS III.
De lucis effectu et irradiatione.
Consequenter quaeritur de lucis effectu et irradiatione. Et circa hoc quaeruntur duo. Primo quaeritur, utrum lumen, quod emittitur a corpore luminoso, sit corpus, an qualitas corporalis. Secundo, dato quod sit qualitas, est quaestio, utrum sit substantialis, vel accidentalis.
Quaestio I. Utrum lumen, quod exit a corpore luminoso, sit corpus.
Circa primum sic proceditur et ostenditur primo, quod lumen, quod exit a corpore luminoso, sit corpus.
Ad oppositum.
1. Omne quod per se movetur localiter et dimensive, est corpus1; sed radius sive lumen egrediens a sole, movetur localiter, utpote ab oriente in occidentem: ergo tam radius quam lumen est corpus.
2. Item, nihil repercutitur et repellitur a corpore nisi corpus; «impossibile enim est, non-corpus a corpore moveri2»; sed luminis et radiorum fit repercussio ad corpus opacum: ergo tam lumen quam radius est corpus.
3. Item, impossibile est, esse confractionem et intersecationem nisi corporum; sed ex repercussione luminis ad speculum concavum fit radiorum intersecatio et confractio: ergo videtur, quod tam lumen quam radius sit corpus.
4. Item, omne quod habet trinam dimensionem, est corpus3; sed lumen in medio habet trinam dimensionem, quia diffunditur secundum omnem positionem, nec tantum est in superficie, immo etiam penetrat aërem usque ad profundum: ergo videtur, quod lumen in medio sit corpus.
5. Item, esto quod sol esset, et circa ipsum esset spatium vacuum, cum sol potens sit ex virtute lucis absque adiutorio extrinseco lumen suum diffundere, nisi habeat resistens, et in illo spatio vacuo nullam habeat resistentiam, ibidem lumen suum diffunderet; sed lumen illud non esset in alio corpore sustinente: ergo videtur, quod esset substantia per se ens4; et non spiritualis, hoc constat: ergo corporalis.
6. Item, quod potest generare corpus est corpus5; sed lumen in medio diffusum potest generare corpus, scilicet ignem, per sui multiplicationem: ergo lumen in medio est corpus.
Ad oppositum:
Fundamenta.
1. Philosophus secundo de Anima6: «Lumen nec est corpus nec defluxus corporis».
2. Item, hoc ratione videtur per suum oppositum. Lumini enim opponitur tenebra privative7: si ergo privatio non est corporis, sed formae, lumen non est corpus, sed forma.
3. Item, hoc videtur per motum. Nullum enim corpus movetur subito secundum locum; sed lux subito alterat, quia in instanti ab oriente venit in occidens: ergo lumen non est corpus. Si tu dicas, quod non movetur subito, sed repente; hoc non potest stare secundum Philosophum8, quia si repente moveretur, id est imperceptibiliter in aliquo spatio, in maiori spatio posset sentiri successio, sicut patet in sono: ergo etc.
4. Item, nullum corpus velocius movetur quam corpus mobilis primi, pro eo quod ille motus est perfectissimus omnium motuum, et ideo velocissimus9; sed lumen ab oriente in occidens multo citius movetur, quam moveatur orbis primus, quia lux in instanti, et illud saltem in duodecim horis: ergo lumen non est corpus.
5. Item, nullum corpus simul et semel movetur ad partes oppositas10; sed lumen simul et semel movetur ad partes oppositas, quia diffunditur sursum et deorsum, ante et retro, a dextris et a sinistris: ergo non potest esse corpus.
6. Item, impossibile est, duo corpora impermixta et non sese augmentantia esse simul; sed lumen cum aëre est impermixtum et ipsum aërem non augmentat, et tamen est simul: ergo non est corpus. Quod autem impossibile sit, duo corpora esse simul, et Philosophus11 dicit, et ad hoc sunt rationes, quae possunt omitti ad praesens, quia inducuntur in quarto, ubi agitur de penetrabilitate corporis gloriosi.
7. Item, nullum corpus habet suum esse in fieri continue; sed lumen in aëre habet suum esse in fieri, quia continue egreditur a sole, sicut dicit Augustinus12: ergo impossibile est corpus esse.
8. Item, si lumen est corpus, aut est ex aliquo, aut est ex nihilo. Si ex nihilo: ergo est a creatione, ergo lumen est a solo Deo, cum ipsius sit creare13. Si ex aliquo; quaero ex quo? aut ex corpore, a quo causatur, aut ex corpore, in quod suscipitur. Constat, quod non ex corpore, in quod suscipitur, quia lumen non producitur ex aëre; tunc enim ibi posset manere, recedente sole. Si ex corpore, a quo causatur: ergo videtur, quod corpus luminosum in emissione luminis aliquid perdit de sua substantia et materia, et ita videtur, quod iam sol deberet esse consumtus.
CONCLUSIO.
Lumen et radius, prout proprie accipitur, non est corpus.
Respondeo: Ad praedictorum intelligentiam est notandum, quod circa hoc quatuor fuerunt opiniones.
Opinio 1. Quidam enim voluerunt dicere, quod tam lumen quam radius in medio corpus est, et egressus ipsorum radiorum ab ipso sole est sicut egressus rivulorum a fonte. Sicut enim a fonte procedunt rivuli, qui sunt corpora et eiusdem naturae cum fonte, sic dicunt esse in radiis et sole. Et si tu obiicias eis, quod videtur, quod substantia solis et aliorum luminarium iam esset pene consumta: respondent, quod sicut non consumitur substantia fontis, pro eo quod, sicut fit emissio, ita fit etiam restauratio; sic dicunt, quod non consumitur substantia solis, pro eo quod, sicut exterius emittit lumen suum inferius, sic virtute radiorum vapores ad se trahit superius, ex quibus restauratur, sicut corpus alimento, adeo ut nec deficiat nec decrescat. Et hoc videtur sensisse Seneca14. — Improbatur. Positio tamen ista est contra philosophiam, quae dicit, corpora caelestia omnino esse incorruptibilia15.
Opinio 2. Secunda vero positio est, quod lumen est corpus, et similiter radii, et processus ipsorum radiorum a sole est sicut ramorum a radice, maxime si ita esset, quod statim radix posset ex se producere arborem, adiuta divina virtute, sicut forte fuit in prima rerum conditione; et sicut radix non diminueretur, si ita produceret arborem, et tamen dicerentur semper rami ab illa radice exire, non quia de novo egrediantur, sed quia cum sua origine continuantur: sic dicunt et in solis radiis se habere. Cum enim Deus solem tanquam originem et principium luminis fecit, simul cum hoc ramificationem radiorum sibi dedit; et sol continue dicitur illos radios emittere, quia illi radii nunquam separantur a sua origine; sed sicut sol movetur, sic radii circumferuntur, non novi generantur; eosdem enim radios, quos emisit a principio super terram, emittit etiam et nunc. — Improbatur. Sed esto, quod sol obscuraretur, sicut in passione Christi creditur esse factum16; tunc videtur, quod oporteret ex tunc radios renovari, et ita de novo creari, si corpora essent.
Opinio 3. Tertia positio est, quod tam lumen quam radius in medio corpus est; et productio eius quantum ad formam est a sole, quantum vero ad materiam est a Creatore. Dicunt enim, quod hoc spectat ad perfectionem universitatis, ut, sicut est aliqua creatura, quae quantum ad materiam et formam immediate est a Deo, ut Angelus, quaedam, quae quantum ad formam est a Deo immediate et quantum ad materiam est a natura, ut homo; sic etiam tertium genus est, quod quantum ad formam est a creatura et quantum ad materiam a Deo. — Improbatur. Sed illud non videtur probabile, cum Deus nunquam creet materiam praeter formam aliquam17.
Licet autem quaelibet harum trium positionum specialiter dicat aliquid improbabile circa originem luminis ex lumine, omnes tamen communiter improbantur per hoc, quod dicunt, lumen in medio esse corpus, tum propter ipsius diffusionem, quae subita est, tum etiam propter coexistentiam cum aëre, quae impermixta est, tum etiam propter ipsius productionem, quae nec est ex materia nec unquam separatur ab eius existentia, immo sicut continue est, ita continue generatur; ut dicit Augustinus18, quod lumen habet permanentiam per continuam solis influentiam.
Opinio 4 et conclusio. Et ideo est quarta positio concors rationi et philosophiae, quod lumen et radius, si nominet illud praecise, quod a luce habet ortum, nec est corpus nec corporis defluxus, sicut rationes ad hoc inductae ostendunt. Si autem dicatur radius aer illuminatus secundum diametrum, et lumen aer illuminatus secundum profundum; sic isto modo radius et lumen poterit dici corpus. — Conclusio 2. Prout tamen proprie accipitur lumen et radius in medio, corpus non est.
Solutio oppositorum.
1. Ad illud ergo quod primo obiicitur, quod movetur localiter; dicendum, quod sicut videmus in specie generata a colore, quod dupliciter movetur, et unus motus est per diffusionem procedendo a corpore obiecto usque ad speculum, alius autem motus, secundum quod videtur moveri in speculo ad motum corporis obiecti — et primus non est motus localis, sed generationis, secundo vero motu non movetur per se, sed per accidens — Distinctio. sic intelligendum est in proposito, quod motus luminis, qui est per egressum ipsius a corpore lucido, non est proprie loci mutatio, sed magis luminis generatio et diffusio; et hoc patet ex hoc, quod fit subito in spatio quantumcumque magno. — Notandum. Motus vero alius, qui est per delationem ipsorum radiorum super terram cum ipso sole, iste est solum per accidens, sicut movetur virtus ipsa ad motum sui principii influentis; et tamen virtus corpus non est. Sic intelligendum est de lumine, quod se habet ad corpus luminosum per modum virtutis influxae. Unde Damascenus19: «Dicimus propter lumen, quod ex ipso provenit, lucere ignem, et non ponimus, ministeriale organum ignis esse, quod ex ipso est lumen, virtutem vero magis naturalem».
2. Ad illud quod obiicitur, quod radii repercutiuntur a corpore; dicendum, quod repercussio alicuius ab aliquo potest esse dupliciter: — Duplex repercussio. quaedam ex collisione duorum sibi invicem obviantium, sicut pila repercutitur a pariete; quaedam ex ineptitudine patientis ad suscipiendam virtutem agentis, et sic repercutitur radius a corpore opaco. Sol enim, sive quodcumque aliud corpus luminosum, habet virtu-
tem diffundendi lumen usque ad aliquod spatium determinatum, cum sit virtutis finitae; et quamdiu se protendit illa virtus, multiplicatur lumen, si susceptibile sit idoneum: — Ad perspectivam. cum vero ante terminationem illius virtutis obviat aliquod corpus, quod non est idoneum ad eius susceptionem, hoc ipso quod lumen non poterat se multiplicare in anterius, multiplicat se retrorsum, non ex virtute corporis resistentis, sed ex virtute primi moventis. Unde cum fit repercussio radii in aqua, mota aqua, movetur radius, non quia aqua sit principium movens, sed prima virtus radium producens, quae, occasione accepta ab aqua, poterat20 radium reflectere, et occasione accepta ab eadem, potest reflexionem variare et ita radium movere. — Quod enim dicitur: impossibile est, non-corpus a corpore repelli21; — Distinctio. dicendum, quod si est aliquid ita non-corpus, quod sit spiritus, hoc verum est. Si autem est ita non-corpus, quod quidem indiget corpore deferente, sic absque dubio repelli potest; sicut praedictum est in lumine, et manifestum est in imagine, quae relucet in speculo propter appositionem plumbi cum vitro, quod est corpus opacum. Si enim esset solummodo vitrum per se, quod est corpus pervium, transiret species et non rediret ad oculum, sicut patet per sensibile experimentum.
3. Ad illud quod obiicitur, quod fit intersecatio22 et confractio radiorum; dicendum, quod hoc dicitur ratione aëris coniuncti, qui ex virtute radiorum ibi concurrentium habet subtiliari et moveri; et ratione illius dicuntur etiam radii confringi, dum ex multiplicatione secundum oppositas vias, per progressum et regressum, fit quaedam multiplicatio et aggregatio luminis et subtiliatio aëris circa corpus tersum; ex qua contingit, effectum calorem radii intendi, et ignem ibidem per caloris intensionem ex aëre sic subtiliato generari.
4. Ad illud quod obiicitur, quod lumen habet trinam dimensionem in medio; — Distinctio. dicendum, quod dimensionem potest aliquid habere dupliciter: vel ex se, vel ex ratione eius, in quo est. Si ex se, sic est corpus; si aliunde, non oportet. Sic enim habet trinam dimensionem albedo in cerussa et nive, quae sunt albae intra et extra23.
5. Ad illud quod obiicitur, quodsi circa solem esset vacuum, quod illuminaret; — De vacuo illuminando. dicendum, quod licet aliqui hoc dixerint, tamen non videtur verum nec probabile. Philosophus enim contrarium sentit in secundo de Anima24, cum dicit, quod «per vacuum non est videre»; et Augustinus similiter in duodecimo Confessionum, in principio dicens sic: «Ubi lux esset, si esset, nisi superesset eminendo et illustrando»? — Ratio etiam est contra hoc, quia, cum lumen sit forma corporalis, indiget medio deferente. Et si tu quaeras, quid impediat; dico, quod hoc non est propter praesentiam impedimenti, sed propter absentiam adiutorii: sicut si aliquis habens magnam famem et carens cibo non potest comedere, non quia impediatur, sed quia non adiuvatur.
6. Ad illud quod obiicitur, quod lumen generat corpus; — Notandum. dicendum, quod lumen non agit propria virtute, sed virtute corporis luminosi; corpus autem luminosum non educit corpus quantum ad materiam, sed solummodo quantum ad formam: et ideo cum lumen sit illud, per quod agit, non oportet, lumen esse corpus, sed sufficit, quod sit forma corporalis.
Auctores vide supra in scholio ad a. 2. q. 1. — In 3. fundam. ex suppositione, quod motus luminis fiat in instante, concluditur, quod non sit corpus. Consentit S. Thom. (S. I. q. 67. a. 2.) his verbis: «Si lumen esset corpus, illuminatio esset motus localis corporis. Nullus autem motus localis corporis potest esse in instanti… illuminatio autem fit in instanti». — Quod autem sonus causetur motu locali, omnes tenebant (cfr. S. Thom., opusc. de Natura luminis). — Suppositio autem, quod motus luminis fiat in instante, falsa est, ut observationibus astronomicis nunc probatum est. Observandum autem est, quod S. Bonav., I. Sent. d. 37. p. II. a. 2. q. 3. ad 1. etiam aliam sententiam ut probabilem refert, quae tenet, motum illum fieri quidem in tempore imperceptibili, non autem instantaneo. — Quod autem non sit proprie motus localis ibi etiam sic explicatur, quod «non est motus localis tantum, sed est motus diffusionis, qui est generatio, sicut generatur idolum ab obiecto; et quia lux simul est et lucet, simul cum est generat splendorem et ita in eodem instanti» (cfr. hic ad 1. et infra d. 14. p. I. a. 3. q. 2. ad 3.). — De quaestione, utrum lumen moveatur in instante, integra quaestione disputat Richard. a Med. (hic a. 2. q. 2.) et in fine concludit, affirmativam sententiam magis esse consonam Philosopho magisque sibi placere.
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## ARTICLE III.
On the effect and irradiation of light.
Next it is asked about the effect and irradiation of light. And concerning this two [things] are asked. First it is asked, whether the lumen which is emitted from a luminous body is a body, or a corporeal quality. Secondly, given that it is a quality, [there is the] question whether it is substantial or accidental.
Question I. Whether lumen, which goes forth from a luminous body, is a body.
Concerning the first it is so proceeded and shown first, that the lumen which goes forth from a luminous body is a body.
Against the opposite.
1. Everything which is moved through itself locally and dimensionally is a body1; but the ray or lumen going out from the sun is moved locally — that is, from east to west: therefore both the ray and the lumen is a body.
2. Likewise, nothing is reverberated and driven back from a body except a body — «for it is impossible that a non-body be moved by a body2»; but reverberation of light and rays occurs at an opaque body: therefore both lumen and ray is a body.
3. Likewise, it is impossible that there be refraction and intersection except of bodies; but from the reverberation of light at a concave mirror occurs an intersection and refraction of rays: therefore it seems that both lumen and ray is a body.
4. Likewise, everything which has the three dimensions is a body3; but lumen in a medium has the three dimensions, because it is diffused according to every position, nor is it only on the surface — rather it even penetrates the air into the depth: therefore it seems that lumen in a medium is a body.
5. Likewise, suppose that the sun existed and around it there were a vacuum: since the sun is able by the power of light, without extrinsic help — unless it has [something] resisting — to diffuse its lumen; and in that vacuum it would have no resistance; in the same place it would diffuse its lumen; but that lumen would not be in another sustaining body: therefore it seems that it would be a substance existing through itself4; and not spiritual — this is established: therefore corporeal.
6. Likewise, that which can generate a body is a body5; but lumen diffused in a medium can generate a body — namely fire — by its multiplication: therefore lumen in a medium is a body.
On the contrary:
Foundations.
1. The Philosopher in the second of On the Soul6: «Lumen is neither a body nor an effluxion of a body».
2. Likewise, this is seen by reason through its opposite. For darkness is opposed to lumen privatively7: if therefore privation is not of body but of form, lumen is not a body but a form.
3. Likewise, this is seen by motion. For no body is moved suddenly according to place; but light alters suddenly, because in an instant it comes from east to west: therefore lumen is not a body. If you say that it is not moved suddenly but quickly [repente]; this cannot stand according to the Philosopher8, because if it were moved quickly — that is, imperceptibly in some space — in a larger space the succession could be sensed, as is clear in sound: therefore etc.
4. Likewise, no body is moved more swiftly than the body of the first movable, because that motion is the most perfect of all motions and therefore the swiftest9; but lumen from east to west is moved much more swiftly than the first orb is moved, because light [moves] in an instant, and that [orb] at least in twelve hours: therefore lumen is not a body.
5. Likewise, no body is moved simultaneously and at once toward opposite parts10; but lumen is simultaneously and at once moved toward opposite parts, because it is diffused upward and downward, before and behind, on the right and on the left: therefore it cannot be a body.
6. Likewise, it is impossible that two unmixed bodies which do not augment one another be simultaneously [in the same place]; but lumen is unmixed with the air, and does not augment the air itself, and yet is simultaneous [with it]: therefore it is not a body. That it is impossible for two bodies to be at once [in the same place], the Philosopher11 says, and for this there are reasons which can be omitted at present, since they are brought forward in the fourth [book], where the penetrability of the glorified body is treated.
7. Likewise, no body has its being in continual coming-to-be; but lumen in the air has its being in coming-to-be, because it continually goes forth from the sun, as Augustine says12: therefore it is impossible that it be a body.
8. Likewise, if lumen is a body, either it is from something or it is from nothing. If from nothing, then it is by creation — therefore lumen is from God alone, since to create belongs to Him alone13. If from something, I ask, from what? either from the body by which it is caused, or from the body in which it is received. It is established that not from the body in which it is received, because lumen is not produced out of the air — for then it could remain there when the sun withdraws. If from the body by which it is caused, then it seems that the luminous body, in the emission of lumen, loses something of its substance and matter, and thus it seems that by now the sun ought to be consumed.
CONCLUSION.
Lumen and ray, as properly taken, is not a body.
I respond: For the understanding of what has been said, it must be noted that on this matter there have been four opinions.
Opinion 1. For some have wished to say that both lumen and ray in the medium is a body, and the going-out of the rays themselves from the sun is like the going-out of streams from a fountain. For just as from a fountain streams proceed, which are bodies and of the same nature as the fountain, so they say it is in the rays and the sun. And if you object to them that it seems that the substance of the sun and of other luminaries would by now be nearly consumed, they answer that, just as the substance of a fountain is not consumed — because as emission occurs, so also restoration occurs — so they say that the substance of the sun is not consumed, because just as outwardly downward it emits its lumen, so by the power of its rays it draws upward vapors to itself, by which it is restored, as a body by food — to such a degree that it neither fails nor decreases. And this Seneca14 seems to have held. — It is disproven. This position, however, is against philosophy, which says that celestial bodies are entirely incorruptible15.
Opinion 2. The second position, however, is that lumen is a body, and similarly the rays — and the procession of the rays themselves from the sun is like that of branches from a root, especially if it were so that the root could immediately produce a tree out of itself, assisted by divine power, as perhaps was the case in the first condition of things; and just as the root would not be diminished if it so produced a tree, and yet the branches would always be said to issue from that root — not because they go forth anew, but because they are continuous with their origin — so they say it is also in the sun's rays. For when God made the sun as the origin and principle of lumen, simultaneously with this He gave to it the ramification of rays; and the sun is continually said to emit those rays because those rays are never separated from their origin; but just as the sun is moved, so the rays are carried around — they are not generated anew; for the same rays which it emitted from the beginning upon the earth, it emits even now. — It is disproven. But suppose that the sun were darkened, as in the passion of Christ is believed to have happened16; then it seems that it would have been necessary from then on for the rays to be renewed, and thus to be created anew, if they were bodies.
Opinion 3. The third position is that both lumen and ray in the medium is a body; and its production as regards form is from the sun, but as regards matter is from the Creator. For they say that this pertains to the perfection of the universe — that, just as there is some creature which as regards matter and form is immediately from God, like an angel; and some which as regards form is immediately from God and as regards matter is from nature, like man; so also there is a third genus, which as regards form is from a creature and as regards matter is from God. — It is disproven. But this does not seem probable, since God never creates matter apart from some form17.
Although, however, each of these three positions specifically says something improbable concerning the origin of lumen from light, nevertheless all of them are commonly disproven by this — that they say lumen in the medium to be a body — both on account of its diffusion, which is sudden; and also on account of its coexistence with the air, which is unmixed; and also on account of its production, which is neither from matter nor ever separated from its [source's] existence; rather, just as it continually is, so it is continually generated; as Augustine says18 that lumen has its permanence through the continual influence of the sun.
Opinion 4 and conclusion. And therefore there is a fourth position, in concord with reason and philosophy: that lumen and ray, if it names precisely that which has its rise from light, is neither a body nor an effluxion of a body, as the reasons adduced for this show. But if ray be called air illuminated according to diameter, and lumen air illuminated according to depth, then in this way ray and lumen can be called a body. — Conclusion 2. But as lumen and ray are properly taken in the medium, they are not a body.
Solution of the opposing [arguments].
1. To that which is first objected, that it is moved locally: it must be said that just as we see in a species generated from color that it is moved in two ways — and one motion is by diffusion, proceeding from the object body to the mirror, but the other motion [is] according as it seems to be moved in the mirror at the motion of the object body — and the first is not local motion, but [motion] of generation; but by the second motion it is not moved through itself, but per accidens — Distinction. so it must be understood in the matter at hand, that the motion of lumen which is by its going forth from the shining body is not properly local change, but rather the generation and diffusion of lumen; and this is clear from this — that it occurs suddenly in however great a space. — Note. The other motion, however, which is by the carrying of the rays themselves over the earth together with the sun itself — this is only per accidens, just as a power itself is moved at the motion of its influencing principle; and yet the power is not a body. So it must be understood of lumen, that it is related to the luminous body in the manner of an influxed power. Hence the Damascene19: «We say, on account of the lumen that proceeds from it, that fire shines; and we do not posit the lumen which is from it to be the ministerial organ of the fire, but rather a more natural power».
2. To that which is objected, that the rays are reverberated from a body: it must be said that the reverberation of something from something can be in two ways. — Twofold reverberation. One, from the collision of two [bodies] meeting one another, as a ball is reverberated from a wall; another, from the ineptitude of the patient to receive the power of the agent — and thus a ray is reverberated from an opaque body. For the sun, or any other luminous body, has the power
of diffusing lumen up to some determinate space, since it is of finite power; and as long as that power extends itself, lumen is multiplied, if there be a suitable receiver; — Concerning perspective. but when, before the termination of that power, some body meets [the ray] which is not suitable for its reception, by this very fact that lumen could not multiply itself further forward, it multiplies itself backward — not from the power of the resisting body, but from the power of the first mover. Hence, when reverberation of a ray occurs in water, with the water moved, the ray is moved — not because the water is the moving principle, but [because] the first power producing the ray, which, with occasion received from the water, could20 reflect the ray, and with occasion received from the same, can vary the reflection and thus move the ray. — As to what is said: it is impossible for a non-body to be repelled by a body21; — Distinction. it must be said that if there is something so non-body that it be a spirit, this is true. But if it is so non-body that it nevertheless needs a body to carry it, then it can without doubt be repelled — as has been said in the case of lumen, and as is manifest in the image which shines back in a mirror because of the application of lead with glass, which is an opaque body. For if there were only the glass by itself, which is a pervious body, the species would pass through and would not return to the eye, as is clear by sensible experiment.
3. To that which is objected, that there occurs intersection22 and refraction of rays: it must be said that this is said by reason of the conjoined air, which by the power of the rays concurring there is subtilized and moved; and by reason of this the rays are also said to be refracted, when from the multiplication along opposite ways, by progression and regression, there occurs a certain multiplication and aggregation of light, and a subtilization of the air around a polished body — from which it happens that the heat-effect of the ray is intensified, and fire is generated in the same place through the intensification of heat from the air so subtilized.
4. To that which is objected, that lumen has the three dimensions in the medium: — Distinction. it must be said that something can have dimension in two ways: either from itself, or by reason of that in which it is. If from itself, then it is a body; if from elsewhere, it is not necessary. For so whiteness in white lead and snow has the three dimensions — [things] which are white inside and outside23.
5. To that which is objected, that if there were a vacuum around the sun, that it would illumine; — On the vacuum and illumination. it must be said that, although some have said this, it nevertheless does not seem true or probable. For the Philosopher holds the contrary in the second of On the Soul24, when he says that «one does not see through a vacuum»; and Augustine likewise in the twelfth book of the Confessions, in the beginning, says thus: «Where would light be, if it were [there], unless it were present, surpassing in shining and illumining?» — And there is also a reason against this — that, since lumen is a corporeal form, it needs a medium to carry it. And if you ask, what would impede [it]: I say that this is not on account of the presence of an impediment, but on account of the absence of help — just as if someone having great hunger and lacking food cannot eat, not because he is impeded, but because he is not helped.
6. To that which is objected, that lumen generates a body: — Note. it must be said that lumen does not act by its own power, but by the power of the luminous body; but the luminous body does not bring forth a body as regards matter, but only as regards form — and on this account, since lumen is that through which it acts, it is not necessary that lumen be a body, but it suffices that it be a corporeal form.
See the authors above in the scholion to a. 2, q. 1. — In fundamentum 3, from the supposition that the motion of lumen occurs in an instant, it is concluded that it is not a body. S. Thomas agrees (S. I, q. 67, a. 2) in these words: «If lumen were a body, illumination would be a local motion of a body. But no local motion of a body can be in an instant… but illumination occurs in an instant». — That sound, however, is caused by local motion, all held (cf. S. Thom., opusc. de Natura luminis). — The supposition, however, that the motion of lumen occurs in an instant, is false, as has now been proved by astronomical observations. It must, however, be observed that S. Bonav., I Sent. d. 37, p. II, a. 2, q. 3, ad 1, also reports another opinion as probable, which holds that that motion does occur in an imperceptible time, not however in an instantaneous [one]. — That, however, it is not properly local motion is also explained there thus, that «it is not local motion only, but is the motion of diffusion, which is generation — just as an idol is generated from the object; and because light at the same time both is and shines, at the same time as it is, it generates splendor, and so in the same instant» (cf. here ad 1, and below d. 14, p. I, a. 3, q. 2, ad 3). — On the question whether lumen is moved in an instant, Richard of Mediavilla disputes in an integral question (here a. 2, q. 2), and at the end concludes that the affirmative opinion is more consonant with the Philosopher and more pleasing to himself.
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- Vide supra pag. 317, nota 5. — Hoc arg., ut patet ex Aristot., II. de Anima, text. 70. (c. 7.), est Empedoclis (et Democriti). Cfr. etiam eiusdem liber de Sensu et sens. c. 3. Avicenna, de Anima seu Sexti Naturalium, p. III. c. 2. hoc et seq. arg. affert pro sententia dicentium, «quod lumen, descendens ex lucido super corpora, non est qualitas, quae contingit eis, sed sunt corpora parvissima, separata a lucido corpore, circumquaque comitantia longitudinem lucidi, designata, quae moventur motu illius, et cum cadunt super corpora, illuminantur ex eis». — In minori post localiter cod. X addit et dimensive.See above p. 317, note 5. — This argument, as is clear from Aristotle, On the Soul II, text 70 (c. 7), is from Empedocles (and Democritus). Cf. also his book On Sense and the Sensed, c. 3. Avicenna, On the Soul or [book] of the Sixth of the Naturalia, p. III, c. 2, adduces this and the following argument for the opinion of those saying that «lumen, descending from the luminous [body] upon bodies, is not a quality which happens to them, but [they] are very small bodies separated from the luminous body, accompanying the length of the luminous [body] all around, designated, which are moved by its motion, and when they fall upon bodies, [those bodies] are illumined from them». — In the minor, after localiter, cod. X adds et dimensive.
- In cod. I bene additur ut dicit auctor Sex principiorum, c. 2. sive de Actione.In cod. I is well added as the author of the Six Principles says, c. 2, or On Action.
- Aristot., IV. Phys. text. 8. (c. 1).Aristotle, Physics IV, text 8 (c. 1).
- Cod. T existens.Cod. T [reads] existens.
- Cfr. supra pag. 15, nota 11, ubi ex Aristot. affertur, quod generans tale est, quale quod generatur.Cf. above p. 15, note 11, where from Aristotle it is adduced that the one generating is such as the one generated.
- Text. 69. (c. 7.).[On the Soul II,] text 69 (c. 7).
- Ita codd. F Y aa, alii codd. cum Vat. principaliter, codd. R cc cum ed. 1 Lumen enim opponitur tenebrae principaliter. Aristot., II. de Anima text. 70. (c. 7.): Videtur autem lumen contrarium esse tenebris; sunt autem tenebrae privatio etc. — Quod privatio non sit corporis, sed formae, docet Aristot., I. Phys. text. 69. (c. 7.).Thus codices F, Y, aa; other codices with the Vatican [edition read] principaliter; codd. R, cc with edition 1 [read] For lumen is opposed to darkness principally. Aristotle, On the Soul II, text 70 (c. 7): Lumen seems to be contrary to darkness; but darkness is privation, etc. — That privation is not of body but of form, Aristotle teaches, Physics I, text 69 (c. 7).
- Libr. II. de Anima, text. 70. (c. 7.) iuxta translationem Arabico-latinam: Et non vere dixit Empedocles neque alius, si aliquis dixit, sicut ipse dixit, quod lux transfertur et vadit in tempore inter terram et circumferentiam, sed imperceptibili a nobis. Iste enim sermo est extra verum et extra apparentiam; possibile est enim, hoc non percipi in brevi spatio, sed non percipi de oriente ad occidentem, magna est differentia valde (μέγα λίαν τὸ αἴτημα). Cfr. etiam de Sensu et sens. c. 3. et 7. (c. 3. et 6.). — IV. Phys. text. 127. (c. 13.) Aristot. dicit: Repente autem, quod in insensibili tempore propter parvitatem remotum est (ἕκταν). — Vat. cum paucis tantum codd. omittit hoc non potest stare secundum Philosophum, quia si repente, et dein post spatio ipsa addit tunc sequitur quod.[Aristotle,] On the Soul II, text 70 (c. 7) according to the Arabic-Latin translation: And Empedocles did not speak truly — nor did anyone else, if anyone said as he said, that light is transferred and goes in [some] time between the earth and the circumference, but [in time] imperceptible to us. For this speech is outside the truth and outside appearance; for it is possible that this not be perceived in a brief space, but not perceived from east to west — there is a very great difference (μέγα λίαν τὸ αἴτημα). Cf. also On Sense and the Sensed, c. 3 and 7 (c. 3 and 6). — Physics IV, text 127 (c. 13), Aristotle says: But quickly [is that] which on account of its smallness is removed in insensible time (ἕκταν). — The Vatican [edition] with only a few codices omits hoc non potest stare secundum Philosophum, quia si repente, and then after spatio itself adds tunc sequitur quod.
- Cfr. supra pag. 19, nota 2.Cf. above p. 19, note 2.
- Vide Aristot., IV. Phys. text. 65. seqq. (c. 8.); VIII. text. 70. et 73. (c. 8.); et I. de Caelo et mundo, text. 5. seqq. et 77. (c. 2. 8.).See Aristotle, Physics IV, text 65 and following (c. 8); VIII, text 70 and 73 (c. 8); and On the Heavens and the World I, text 5 and following, and 77 (c. 2, 8).
- Libr. IV. Phys. text. 8. 47. 63. (c. 1. 6. 7.); III. de Caelo et mundo, text. 54. (c. 6.); I. de Gener. et corrupt. text. 32. 35. (c. 5.); II. de Anima, text. 69. (c. 7.). — Cfr. IV. Sent. d. 49. p. II. art. princ. 2. a. 3. q. 1. — Cod. cc et ed. 1 inducentur pro inducuntur, et dein post quarto in cod. F additur libro, 49. dist.[Aristotle,] Physics IV, text 8, 47, 63 (c. 1, 6, 7); On the Heavens and the World III, text 54 (c. 6); On Generation and Corruption I, text 32, 35 (c. 5); On the Soul II, text 69 (c. 7). — Cf. IV Sent. d. 49, p. II, art. princ. 2, a. 3, q. 1. — Cod. cc and edition 1 [read] inducentur for inducuntur; and then after quarto in cod. F is added libro, 49. dist.
- Libr. VIII. de Gen. ad lit. c. 12. n. 26. Vide tom. I. pag. 786, nota 9.[Augustine,] On Genesis according to the Letter VIII, c. 12, n. 26. See volume I, p. 786, note 9.
- Cfr. supra d. 7. p. II. a. 2. q. 2. in corp. — Aliquanto inferius cod. cc et ed. 1 ex ipso aëre pro ex aere.Cf. above d. 7, p. II, a. 2, q. 2, in the body. — A little later cod. cc and edition 1 [read] ex ipso aëre for ex aere.
- Libr. I. Natural. Quaest. c. 2. seqq.[Seneca,] Natural Questions I, c. 2 and following.
- De quo vide supra d. 3. p. I. a. 1. q. 2, d. 12. a. 1. q. 2, d. 12. a. 2. q. 1, et infra d. 14. p. I. a. 1. q. 2.On which see above d. 3, p. I, a. 1, q. 2; d. 12, a. 1, q. 2; d. 12, a. 2, q. 1; and below d. 14, p. I, a. 1, q. 2.
- Luc. 23, 45: Et obscuratus est sol.Luke 23, 45: And the sun was darkened.
- Cfr. supra d. 1. p. I. a. 3. q. 1. 2, d. 12. a. 1. q. 1.Cf. above d. 1, p. I, a. 3, q. 1, 2; d. 12, a. 1, q. 1.
- Libr. VIII. de Gen. ad lit. c. 12. n. 26.[Augustine,] On Genesis according to the Letter VIII, c. 12, n. 26.
- Supple cum ed. 1 est.Supply with edition 1 est.
- Libr. I. de Fide orthod. c. 8.[John Damascene,] On the Orthodox Faith I, c. 8.
- Vat. poterit.The Vatican [edition reads] poterit.
- Nonnulli codd. moveri et repelli. Dein cod. T sic est verum pro hoc verum est.Some codices [read] moveri et repelli. Then cod. T [reads] sic est verum for hoc verum est.
- Plurimi codd. cum edd. 1, 2 intersectio, licet in ipsa obiectione posuerint intersecatio.Very many codices with editions 1, 2 [read] intersectio, although in the objection itself they put intersecatio.
- Aristot., I. Ethic. c. 6: Eadem in nive et cerussa albedinis ratio est.Aristotle, Nicomachean Ethics I, c. 6: The account of whiteness in snow and in white lead is the same.