Capitulum 3 Chapter 3 Sight is constituted of water Democritus autem quoniam quidem aquam dicit esse, bene dicit, quia autem putavit ipsum videre esse apparitionem, non bene: hoc enim accidit quoniam oculus levis est, et est non in illo, sed in vidente; passio enim refractio est. Sed omnino de apparentibus et de refractione nondum ipsi manifestum erat, ut videtur. Democritus says correctly that it is water, but not correctly that he thought that the appearance is the seeing itself. For this occurs because the eye is smooth. And it is not in that, but in what is doing the seeing. For the affection is a reflection. But it seems that it was not yet clear to him about appearances and reflection. Incongruum autem est et non supervenire ipsi dubitare quare solus oculus videt, nullum autem aliorum in quibus apparent idola. But it is inconsistent that it also did not occur to him to wonder why only the eye sees, and none of the other things in which “idols” appear. Quod visus namque est aquae, verum quidem, non tamen accidit videre secundum quod aqua est, sed secundum quod est perspicuum, quod et aeri commune est. Sed magis servabilius est aqua aere et magis spissum; quare pupilla et oculus aquae sunt. For it is indeed true that sight is made of water, but seeing does not occur according as it is water, but according as it is transparent, which is something common to it and air. But water is more preservable than air and denser, which is why the pupil and eye are made of water. Et hoc est et in ipsis operibus manifestum; videtur enim aqua quod discurrit corruptis oculis, et in omnino noviter formatis frigiditate excedens et claritate, et album oculi in habentibus sanguinem pingue et crassum; propter hoc est ut permaneat humidum incoagulatum, et ideo corporis minime rigens est oculus; nulli enim unquam quod infra palpebras est riguit. Animalium vero quae sine sanguine sunt, dure pellis sunt oculi, et hoc facit protectionem. This is manifested in the very workings. For when eyes are destroyed, water can be seen flowing out. And in completely new-formed ones, there is extreme cold and brightness. And in those that have blood, the white of the eye is fat and thick, to keep the moisture unfrozen; and so the eye is the part of the body that feels cold least, for no-one has ever felt cold inside the eyelids. The eyes of bloodless animals are made of hard skin, and this provides protection. Irrationabile vero omnino est exeunte quodam visum videre, et aut extendi usque ad astra, aut quodam tenus prodeuntem coadherere, sicut quidam dicunt. It is altogether irrational that sight should see by something going out, whether it extends all the way to the stars, or, as some say, it goes only so far and “coalesces.” Isto enim melius est in principio coniungi oculi. For in the latter case it is better for it to be united at the beginning, that is, in the eye. Sed et hoc stultum: quid enim coniungi est lumen lumini? Vel quomodo possibile hoc esse: non enim quodlibet coniungitur cuilibet. Et interius exteriori quomodo? Miringa enim interest. But this is also foolish. For what is it for light to be “united” to light? Or how is it possible, since not just anything is united with anything? And how is the inner light united with the outer, since the membrane is between? Democritus autem quoniam quidem aquam etc. Post opinionem Platonis et Empedoclis, hic tertio Philosophus prosequitur de opinione Democriti. Et circa hoc tria facit: Democritus says correctly that it is water (438a5). After the opinions of Plato and Empedocles, here, in the third place, the Philosopher follows up the opinion of Democritus. On this point he does three things. primo ostendit in quo Democritus bene dixit et in quo male; First he shows what Democritus said correctly and what he said incorrectly. secundo prosequitur illud in quo male dixit, ibi: incongruum autem est etc.; Second he follows up what he said incorrectly, where he says: but it is inconsistent (438a10). tertio prosequitur illud in quo bene dixit, ibi quod visus namque etc. Third he follows up what he said correctly, where he says: for it is indeed true that sight is made of water (438a12). Dicit ergo primo quod Democritus bene dixit in hoc quod visum attribuit aquae, sed in hoc male dixit quod putavit visionem non aliud esse quam apparitionem rei visae in pupilla; huiusmodi enim apparitio fit in pupilla ex corporali dispositione oculi, quia scilicet oculus est laevis, id est quasi politus et tersus, et ita patet quod ipsum videre non consistit in hoc quod est apparere talem formam in oculo, sed consistit in vidente, id est in habente virtutem visivam: non enim oculus est videns propter hoc quod est laevis, sed propter hoc quod habet virtutem visivam; illa enim passio, scilicet quod forma rei visae in oculo appareat, est refractio, id est causatur ex refractione sive reverberatione formae ad corpus politum. Accordingly he first says that Democritus spoke correctly in assigning sight to water, but he spoke incorrectly in saying he thought that vision is nothing but the appearance in the pupil of the thing seen. For such an appearance occurs in the pupil because of the bodily disposition of the eye, that is, because the eye is smooth, that is, polished and clean, as it were. So it is clear that seeing itself is not located in the appearance of this form in the eye, but in what is doing the seeing, that is, in what has the power of sight: for the eye is a seeing thing not because it is smooth, but because it has the power of sight. For that affection—the appearing of the form of the thing seen in the eye—is a reflection; that is, it is caused by the reflection or rebound of the form from a polished body. Sicut etiam videmus in speculo accidere; cum enim immutatio diaphani quae fit a corpore visibili pervenerit ad corpus non diaphanum, non potest ultra immutatio transcendere, sed quodam modo reflectitur, ad similitudinem pilae quae repercutitur proiecta ad parietem, et ex tali repercussione redit forma rei visae ad partem oppositam; unde contingit quod aliquis in speculo videt se ipsum vel etiam aliam rem quae non directe visui eius obiicitur. We see something like this happen in a mirror also. For when the alteration of the transparent caused by a visible body reaches a body that is not transparent, the alteration can go no further, but is somehow turned back, like a ball thrown at a wall and bounced back, and because of this rebound the form of the thing seen goes back in the opposite direction. Thus in a mirror one can see oneself, or even some other thing not directly presented to one’s sight. Sed hoc locum non habet nisi duo concurrant, quorum unum est ut corpus sit superficie laeve et ex hoc quodam modo fulgens, ut supra dictum est, per quem fulgorem moderatum manifestatur species in reflexa; aliud est ut corpus illud sit interius ad aliquid terminatum, ut immutatio praedicta ultra non transeat: et ideo videmus quod nisi vitro apponatur plumbum vel aliquod huiusmodi quod impediat eius pervietatem ne ulterius procedat immutatio, non fit talis apparitio. This takes place only if two things coincide. One is that the body be smooth on its surface, and therefore somewhat bright, as was explained above; the form reflected in it is manifested by this moderate brightness. The other is that the body be terminated within at some point so that the above-mentioned alteration does not go beyond; thus we see that this kind of appearance does not occur, unless glass is covered with lead or something similar to block its transparency, so that the alteration does not go beyond. Utrumque autem horum concurrit in oculo: est enim moderate fulgens propter laevitatem, ut supra habitum est, et iterum habet aliquid in fundo quod terminet eius pervietatem. Unde manifestum est quod hoc accidens, scilicet quod forma rei visae appareat in oculo, accidit pure propter refractionem, quae est passio corporalis causata ex determinata corporis dispositione. Now both of these coincide in the eye: it is moderately bright because of its smoothness, as was established above, and it has something in its depth that terminates its transparency. So it is clear that this event of the form of the thing seen appearing in the eye happens merely because of reflection, which is a bodily affection caused by the determinate disposition of a body. Democrito tamen nondum erat manifestum de huiusmodi refractionibus et de formis quae apparent in corporibus specularibus propter refractionem praedictam. Ipsa autem visio secundum rei veritatem non est passio corporalis, sed principalis eius causa est virtus animae; Democritus tamen ponebat animam esse aliquid corporale et ideo non est mirum si operationem animae nihil aliud esse dicebat quam passionem corporalem. But it was not yet clear to Democritus about these reflections and about the forms that appear in mirroring bodies because of reflection. Vision itself, according to the truth of the matter, is not a bodily affection: rather, its principal cause is a power of soul. But Democritus held that soul is something bodily, and so it is no wonder that he called an operation of soul nothing but a bodily affection. Sciendum tamen quod praedicta apparitio, quantum ad primam receptionem formae, est quaedam <causa> visionis: non enim visio est actus animae nisi per organum corporeum et ideo non est mirum si habeat aliquam causam ex parte corporeae passionis, non tamen ita quod ipsa corporea passio sit idem quod visio, sed aliqua causa eius quantum ad primam, ut ita dicam, percussionem formae visibilis ad oculum. Nam reflexio consequens nihil facit ad hoc quod oculus videat rem visam per speciem in eo apparentem, sed facit ad hoc quod alteri possit apparere; unde etiam oculus videns rem per speciem, non videt ipsam speciem in eo apparentem. It should be known, however, that the above-mentioned appearance is a cause of vision with respect to initial reception of the form. For vision is an act of soul only through a bodily organ, and so it is no wonder that it has a cause from the point of view of a bodily affection, but in such a way that the bodily affection is not the same thing as the vision: rather, it is a cause of it with respect to the initial “impact,” if I may so call it, of the visible form on the eye. The subsequent reflection contributes nothing to the eye’s seeing of the thing seen through the form appearing in it, but rather contributes to the form’s being able to appear to someone else; thus the eye that sees the thing by means of the form that appears in it does not see this form itself. Deinde cum dicit: incongruum autem etc., prosequitur quantum ad hoc quod Democritus male dixit. Then, when he says: but it is inconsistent (438a10), he follows up what Democritus said incorrectly. Et dicit quod valde incongruum videtur quod Democrito ponenti visionem nihil aliud esse quam apparitionem praedictam non occurrerit ista dubitatio, quare alia corpora in quibus formae rerum visibilium, quas idola nominabat, specialiter apparent, non videant, sed solus oculus. Ex quo manifeste apparet quod non tota ratio visionis est praedicta apparitio, sed in oculo est aliquid aliud quod visionem causat, scilicet virtus visiva. He says that since Democritus held that vision is nothing but the above-mentioned appearance, it seems very inconsistent that the following difficulty did not occur to him: why do other bodies in which forms—which he called idols—of visible things appear as in a mirror not see, but only the eye? From this it is clear that the above-mentioned appearing is not the whole essence (ratio) of vision, but that there is something else in the eye that causes vision, namely the power of sight. Deinde cum dicit: quod visus namque etc., prosequitur id quod Democritus bene dixit. Then, when he says: for it is indeed true that sight is made of water (438a12), he follows up what Democritus said correctly. Et primo proponit veritatem; First he presents the truth. secundo manifestat per signa, ibi et hoc est et in ipsis operibus etc. Second he clarifies it by signs, where he says: this is manifested (438a17). Dicit ergo primo quod hoc Democritus organum visus attribuit aquae, verum est, sciendum tamen quod visio attribuitur aquae non secundum quod est aqua, sed ratione perspicuitatis, quae communiter in aqua et aere invenitur: nam visibile est motivum perspicui, ut dicitur in libro De anima. Attribuitur tamen visio magis aquae quam aeri propter duo: Accordingly he first says that what Democritus said in assigning the organ of sight to water is true. However, it must be known that vision is assigned to water not according as it is water, but by reason of transparency, which water and air have in common: for a visible object is something that moves the transparent, as is said in the book On the Soul. However, vision is assigned to water rather than to air for two reasons. primo quidem quia aqua magis potest conservari quam aer (aer enim de facili diffunditur) et ideo ad conservationem visus convenientior fuit aqua quam aer, natura autem semper facit quod melius est; s First, water can be preserved better than air (air is easily dispersed), and so it is more suitable for the preservation of sight than is air, and nature always does what is better. ecundo quia aqua est magis spissa quam aer et ratione suae spissitudinis habet quod in ea per quamdam reverberationem appareat forma rei visae, et hoc competit instrumento visus; Second, water is denser than air, and by reason of its density it allows the form of a thing seen to appear in it by reflection, which is proper to the organ of sight. esse autem pervium competit medio in visu, quod commune est aeri et aquae; et ideo concludit quod oculus et pupilla magis attribuuntur aquae quam aeri. What is proper to the medium of sight is to be transparent, which is common to air and water. So he concludes that the eye and pupil are to be assigned to water rather than to air. Est etiam et corpus caeleste perspicuum, sed quia non venit in compositionem corporis humani, propter hoc hic praetermittitur. The heavenly body is also transparent, but because it does not enter into the composition of the human body, he passes over it here. Deinde cum dicit: et hoc est etc., manifestat <quod> organum visus esse aquae, per tria signa quae in ipsis operibus manifesta sunt, Then, when he says: this is manifested (438a17), he shows that the organ of sight is made of water by three signs that are manifested in the very workings. quorum primum est quod, si oculi destruantur, ad sensum apparet inde aqua discurrens; The first is that if the eyes are destroyed, there visibly appears water flowing out of them. secundum est [quod] in oculis embryonum de novo formatis qui, quasi adhuc retinentes magis virtutem sui principii, excedunt et in frigiditate et in claritate, quae duo sunt connaturalia aquae; The second is that the new-formed eyes of embryos—eyes that, as it were, still retain much of the power (virtus) of their origin—have abundant cold and brightness, both of which are connatural to water. tertium signum est quod in animalibus habentibus sanguinem, in quibus potest esse pinguedo quasi ex sanguine generata, circa pupillam ponitur album oculi habens pinguedinem et crassitudinem quamdam, ut ex eius caliditate permaneat aqueum pupillae humidum absque congelatione, quae diminueret pervietatem aquae et sic impediretur visio; et ideo ratione praedictae pinguedinis oculus non frigescit propter eius caliditatem: nullis enim unquam passus est frigus in toto eo quod infra palpebras continetur. The third sign is that in animals that have blood, in which there is the possibility of generating, so to speak, fat from the blood, the pupil is surrounded by the white of the eye, which has fatness and oiliness so that its heat will keep the water-moisture of the pupil from freezing, which would diminish the transparency of the water, and thus impede vision. And so, by reason of the above-mentioned fat, the eye, because of its heat, does not freeze: for no-one has ever suffered cold in the whole of what is contained inside the eyelids. In animalibus vero quae sunt sine sanguine, in quibus non invenitur pinguedo, natura fecit oculos durae pellis, ad protegendum humidum aqueum quod est infra pupillam. In animals that are bloodless, in which there is no fat, nature made eyes of hard skin to protect the water-moisture that is in the pupil. Deinde cum dicit: irrationale vero est omnino etc., accedit ad improbandum quod aliqui posuerunt visionem fieri extramittendo, quod erat ratio attribuendi visum igni: unde hoc remoto, et illud removetur. Et circa hoc duo facit: Then, when he says: it is altogether irrational (438a25), he goes on to disprove what some held, namely that vision occurs by extromission, which was the reason for their assigning sight to fire. Thus, once the latter is eliminated, the former will be too. On this point he does two things. primo proponit duas opiniones ponentium quod videmus extramittendo; First he presents two opinions of those who held that we see by extromission.