Giuseppe Veltri The Deceit of the Senses: Sight and the Mirror

According to Pyrrho, as is transmitted by Aristocles via Eusebius of Caesarea, knowl- edge acquired through the senses is neither true nor false: “Now he says that Pyrrho shows that objects are equally indifferent and unfathomable and undeterminable because neither our senses nor our judgements are true or false.”1 If our senses and therefore our judgments do not fulfil the criteria of the Aristotelian principle of con- tradiction, being neither true nor false, they are either equipollent or insufficient for perception. The suspension of judgment is not only logical but also necessary. According to the Pyrrhonian Sextus Empiricus, the main argument for necessary invalidation of knowledge is “disagreement”2 because of the difference of the senses,3 for it is obvious to him that senses differ from one another. He also quotes some exam- ples of discrepancies in perception. Sextus does not question the fact that an object could show the quality of what it is appears to be (“it is possible to say what they appear to be like on any given occasion”).4 However, we are not seeking the percep- tion of the object in its appearance in a particular moment and in a particular space, but the perception according to its real nature. For then the object does not “natu- rally” have any qualities. Each of the phenomena perceived by the senses seems to be a complex: the apple, for example, seems smooth, odorous, sweet, and yellow. However, it is not clear whether it really possesses these qualities, whether it has but one quality that appears varied owing to the varying structure of the sense organs, or whether it has more qualities than are actually apparent to our senses.5 Besides the elusive impact of objects on our senses, there are also the illusions that can be provoked by them, as mentioned by Sextus in a peculiar point of the Out- lines, often cited by modern scholars, in his reference to painting: “paintings seem to sight to have recesses and projections, but not to touch.”6 Recesses and projections are a known element of geography that painters often imitate in their works; they deceive the ocular senses but not the sense of touch.7 Later on, Sextus returns to

1 Eusebius, Praeparatio Evangelica, 14.18.2–4, quoted in Jula Annas and Jonathan Barnes, The Modes of Scepticism: Ancient Texts and Modern Interpretations (Cambridge: Cambridge University Press, 1985), 11. 2 See Markus Lammenranta, “The Role of Disagreement in Pyrrhonian and Cartesian Skepticism,” in Disagreement and Skepticism, ed. Diego E. Machuca (New York: Routledge, 2012), 46–65. 3 Sextus Empiricus, Outlines of Scepticism, ed. and trans. by Julia Annas and Jonathan Barnes (Cam- bridge: Cambridge University Press, 2000), 1.91–2 and following. 4 Sextus Empiricus, 1.93. 5 See Sextus Empiricus, 1.94. 6 Sextus Empiricus, 1.92; see Annas and Barnes, The Modes of Scepticism, 69–71. 7 While it is true that a painting cannot fool the sense of touch, it is not the case for bas-reliefs or impressions made on wax. Sextus does not discuss this kind of art. https://doi.org/10.1515/9783110557602-013 The Deceit of the Senses: Sight and the Mirror 521 the topic of projection and the faculty of sight, again using the example of painting and its apparent rendering of objects that appear different if seen from one angle or another:

Depending on positions: the same picture when laid down appears flat, but when put at a certain angle seems to have recesses and projections. Doves’ necks appear different in colour depending on the different ways they turn them. Since, then, all apparent things are observed in some place and from some interval and in some position, and each of these produces a great deal of variation in appearances, as we have suggested, we shall be forced to arrive at suspension of judgement by these modes too.8

The condition of the object produces divergence in the impression of senses, which necessarily leads to the suspension of judgment. Sextus attaches great impor- tance only to the object which is responsible for the differences in perception. In this context, he does not attack the reliability of the eyes in their perception; rather, he stresses the divergence of the sources of the senses. Luzzatto offers very similar argumentation in his long and complex discussion of the deceitful sense of sight and the correlating debate on the mirror, also a topic of Sextus. In Luzzatto’s little history of ophthalmology,9 which follows the topic of the discoveries and fallacies of the telescope, he displays his acquaintance with ancient, medieval and modern theories of human eyesight.10 It is well known that ancient, medieval, and early modern discussions conducted on the senses mostly relied on Aristotle’s De Anima in its multifaceted interpretations, receptions, and commentaries.11 In the second book of De Anima, Aristotle discusses sense perception in general (chapters 5 and 6), devoting chapter 7 to eyesight. For Aristotle the problem is not whether perception is caused by the objects of percep- tion, but how this is achieved and where it takes place.12 It is no surprise then that both question are objects of Luzzatto’s summary of visual perception. I emphasise the word “summary,” because he does not care to report on the development of ophthal- mology but only its theories.

8 Sextus, Outlines of Scepticism 1.120–21. 9 See Waldemar Deonna, Le Symbolisme de l’Œil (Paris: Broccard, 1965). 10 On ancient and medieval theories see David C. Lindberg, Theories of Vision from Al-Kindi to ­Kepler (Chicago: University of Chicago Press, 1967); Gérard Simon, Le regard, l’être et l’apparence dans l’Op- tique de l’Antiquité (Paris: Edition du Seuil, 1988); Robert Nelson, Visuality Before and Beyond the Renaissance: Seeing as Others Saw (Cambridge: Cambridge University Press, 2000). On the echoes of ancient and medieval theory in poetry (Dante), see Burt Kimmelman, “Visionary Science in Purgatorio XVII and Paradiso XXX,” Comitatus 26 (1995): 53–74. 11 For the reception of the De Anima in the early modern period, see Sascha Salatowsky, De Anima. Die Rezeption der aristotelischen Psychologie im 16. und 17. Jahrhundert (Amsterdam: Grüner, 2006). 12 See Nicholas J. Wade and Michael Swanston, Visual Perception: An Introduction (New York: Psy- chology Press, 2013), 37; T.K. Johansen, Aristotle on the Sense-Organs (Cambridge: Cambridge Univer- sity Press, 1998). 522 The Deceit of the Senses: Sight and the Mirror

Despite the complexity of his enumeration of varied opinions on human vision, Luzzatto’s account is very complex. He notes that the discussion on the formation of images in optical perception is often very detailed and the conclusions reached are highly divergent. He lists the different opinions on the effusion of the image from the object to the eye as well as opinions on the place where the image is formed. First, he elucidates three theories on the modalities of sight, listing them as follows:

– Some of them, as Crito already singled out, considered vision to be carried out by the efflu- vium of rays extending to an object. – Others did not accept this remote ejection and considered that the rays would first match the external light and then, once consolidated together, extend as far as the object. – Furthermore, others argued against the emission of rays and rather asserted that some images and simulacra, once detached from the objects, would enter into the eyes and that they were divided into two classes: some people thought that these images were the mate- rial remains of visible bodies, detached from the objects by the virtue and effectiveness of light; others thought that they were immaterial but proper instruments for leading us to acknowledge material objects, as they were their progenitors, although these simulacra were insensitive by themselves. – There were others who considered that sight could be carried out without the intromission of simulacra or the emission of rays, but that the presence of the object was sufficient for it to be able to encounter the visual faculty.13

An exploration of the many theories concerning sight throughout the ages is a project for another book. Here I simply seek to elucidate three theories that ancient authors were divided between: the theory that rays radiate from the eyes (emission theory); the theory that images come to the eye (intromission theory);14 and the theory that claims that the problem is how the object is received by the eyes via light and is then interpreted by the mind (reception theory), of which the most important representa- tive is Aristotle.15 The emission theory was split into two explanations of the process: the first – supported by Pythagoras, Euclid (in Optics), Ptolemy, and Leon Battista Alberti (in De pictura)16 – claimed that rays directly pass from the eyes to objects; the second – which was the Platonic conception of vision – claims that the rays emitting from the eyes have to meet with the light. This explanation is also called “the mixed theory” because light has to been emitted both by the eyes and the objects. In the Timaeus,

13 Simone Luzzatto, Socrates, 96 (all translations are taken from the present volume). 14 See Wade and Swanston, Visual Perception, 36. 15 See Harold E. Henkes and Claudia Zrenner, eds., History of Ophthalmology: Sub auspiciis Acade- miae Ophthalmologicae Internationalis, Vol. 3 (Dodrecht: Kluwer Academic Publishers, 1990). 16 Leon Battista Alberti, On Painting and on Sculpture, ed. and trans. Cecil Grayson (London: Phaidon, 1972), 40–41. See Jack M. Greenstein, “On Alberti’s ‘Sign’: Vision and Composition in Quattrocento Painting,” The Art Bulletin 79, no. 4 (December 1997): 669–98. The Deceit of the Senses: Sight and the Mirror 523

Plato writes that the “pure fire” within us compresses the central part of the eye in particular,

so that it kept out everything of a coarser nature, and allowed to pass only this pure element. When the light of day surrounds the stream of vision, then like falls upon like, and they coalesce, and one body is formed by natural affinity in the line of vision, wherever the light that falls from within meets with an external object. And the whole stream of vision, being similarly affected in virtue of similarity, diffuses the motions of what it touches or what touches it over the whole body, until they reach the soul, causing that perception which we call sight.17

The intromission theory postulates that tiny atoms or skins (Greek eidōla; Latin sim- ulacra) of the objects detach from the bodies of the objects while retaining object’s image, coming to the eye and thereby generating vision. Democritus, Leucippus, Epicurus, and Lucretius subscribe to this theory.18 According to Democritus, this is enabled by the interaction of the eidōla with the internal light of the viewer (doctrine of the efferent and afferent light).19 Luzzatto’s divides the reception theory, which denies that rays are emitted from the eyes, into three groups: a group that assumes that images are material remainders of visible bodies, cut off from the objects by virtue of the light; a group that maintains that images are immaterial, but permits recognition of the objects as their remote generators or emissions (for Luzzatto: progenitors); and a group that rejects all trans- mission through images and emission of rays, arguing that the presence of the object itself is sufficient for the faculty of sight.20 He goes further:

The location in which vision occurs in us, and whether this also happens through the intromis- sion of simulacra, encounters a similar opposition of opinions and views: – Some believed that it happens in the middle of the crystalline or glacial lens. – Some others could not bear the idea that it could be produced in a simple humour [i. e. the glacial humour] lacking in life and perception and believed that it is carried out in the retinal membrane, located in the innermost secret meanderings of the eye. Nevertheless, they attributed perception to this without paying enough attention to the fact that the images penetrating into it meet and cross, so that the right [image] becomes the left and the higher [image] becomes the lower. – Others who cared even less about this believed that the images intruded as far as the optic nerves in order to avoid objects being duplicated because of the duplicity of those same eyes, as often happens to drunk and delirious people. They indeed did not consider the alteration of images which would necessarily result if they passed through these very narrow mean- derings [i. e. the nerves]. – Others did not agree with attributing this function to any solid part of the eyes, but rather [attributed it] to a spirit permeating the whole eye. [They supposed] that this spirit, which

17 Plato, Timaeus, trans. Benjamin Jowett (Indianapolis: Bobbs-Merrill, 1949), 45a–46a. 18 David C. Lindberg, ed., Science in the Middle Ages (Chicago: University of Chicago Press, 1978), 340. 19 Henkes and Zrenner, History of Ophthalmology, 60. 20 Luzzatto, Socrates, 96–97. 524 The Deceit of the Senses: Sight and the Mirror

is of a very feeble and fluid condition, could stop and halt images, an [action] that is not even possible for water, naturally more solid than this, though it is wrong of me to mention water – indeed, it would not even be possible for a crystal to do this. – Others tried to accommodate all of the aforementioned opponents’ opinions and they said that vision works through the simulacra’s encounter with the heap of membranes, humours, nerves, and spirits located in the eyes. Thus, they thought to generously satisfy their mutual friends and were content with merely tolerating all the oppositions encountered for each of the aforementioned opinions.21

In this list, Luzzatto presents a number of divergent opinions in reference to the inner place (loco interno) where sight takes place through an intermediary agency by images. Some opine that the intermediary is in the crystalline lens.22 Others reject the idea that sight can take place in a humour which is lifeless and senseless and attribute it to the membrane of the retina (membrana rettina) located in the innermost interior of the eye.23 Uninterested in the problem of how the images convert them- selves optically, Luzzatto adds that an advocate of the last opinion assumes that the rays have to unify themselves in the optical nerves so that we do not see double, as the intoxicated do. Luzzatto attacks the notion of the unification of these images in the optical nerve. He argues that its supporters do not take into account the “corruption” (depravatione) of the images as they traverse the very tiny holes.24 A last group does not accept the attribution of this function to a solid material, and instead proposes a permeable spirit.25 Luzzatto questions whether a permeable spirit that is fluid in nature can be impressed upon by images at all. With an argument a maiori, he doubts that a fluid spirit can “stop” images if water and even crystal cannot. Luzzatto dismisses every scientific and philosophical attempt to explain the process of sight as “inclination to contradiction,” a result of human curiosity. Against

21 Luzzatto, 97. 22 That vision takes place in the crystalline lens was the opinion of Galen. The lens was described as a round lens in the middle of the eye: “the crystalline lens is the principal instrument of vision, a fact clearly proved by what physicians call cataracts, which lie between the crystalline humor and the cornea and interfere with vision until they are couched.” May M. Tallmadge, ed., Galen and the Use- fulness of the Parts of the Body (Ithaca: Cornell University Press, 1968), 463–64. See Julius Hirschberg, Geschichte der Augenheilkunde (Berlin: Springer, 1899–1919), 1: § 102; § 115. The anatomist Vesalius also reported the opinion of Galen and still believed that the lens is the centre of the eyeball, see Hirschberg, 2: § 305. 23 That was the postulation of Felix Plater, De corporibus humani structura et usu (Basel: Abrosium Frob, 1583), 187, quoted in Hirschberg, Geschichte der Augenheilkunde, 2: § 306 (p. 290n179), perhaps in appreciation of Kepler’s A Sequel to Vitello (1604). The author of the idea seems to be Hieronymus Fabricius ab Aquapendente, a professor from the University of Padua, specifically in his De Actione Oculorum. See Hirschberg, 3: § 66. 24 Luzzatto, Socrates, 98. 25 It is difficult to say what Luzzatto’s reference to spirito permabile means. It may refer to Galen’s theory of pneuma, which had a vivid reception in the Renaissance, also with the help of Melanchthon. See Jürgen Helm, “Die Galenrezeption in Philipp Melanchthons De Anima (1540/1552),” Medizinhisto- risches Journal 31 (1996): 298–321. Perhaps he is referring to the theory of the spiritus visibilis of Ibn al-Hayṯam (Alhazen), on which see Hirschberg, Geschichte der Augenheilkunde, 3: § 63. The Deceit of the Senses: Sight and the Mirror 525 the Aristotelian principle of perception according to which “each sense discerns these [proper objects] and is not deceived,”26 he substantiates his conviction that the problem remains the deceptions of the images themselves and, of course, the eyes:

Yet which of these aforementioned opinions is the truest does not really concern my proposal. The reason for this is that I did not put forth these opinions to debate them, but I want to infer from this collection of various opinions only this: regardless of whether vision happens in this way or in other ways, it is necessary [to point out] that there is a great diversity between the appearance of objects and their true reality. Who may deny that the representation of what is visible would dramatically change if it happened through the emission of rays as far as the object, or by these [rays] mingling with the light, or rather by the intromission of images, or by the simple presence of the object, as well as whether it was carried out in the middle of the glacial or the retinal membrane, or throughout the optic nerves, or in spirits, or in all of them clustered together?27

The Rabbi of Venice’s main point is clearly formulated: “there is a great diversity between the appearance of objects and their true reality.” When he first mentions the attempts to explain the process of vision taken as a whole, he returns to his premise of the dialectical confrontation with dogmatic philosophy, turning his attention to the deceitful source of knowledge that is the mirror, which is a prime example of the great difference between the appearance and the reality of objects.28 That Luzzatto discusses mirrors is not surprising, as mirror production was an important industry in Venice.29 However, he is still following the contours of the dis- cussion on the senses and sight shaped by Sextus, who discusses mirrors in his Out- lines after presenting the argument of the first topos according to which the “same impressions are not produced by the same objects owing to the differences in ani- mals.”30 Sextus introduces the example of mirrors as follows:

Mirrors, depending on their differing constructions, sometimes show external objects as minute (e. g. concave mirrors), sometimes as elongated and narrow (convex mirrors); and some of them show the head of the person reflected at the bottom and their feet at the top. Since, then, some of the vessels of sight protrude and project beyond the body because of their convexity, while others are more concave and others are set level, it is likely that the appearances are altered by this too, and that dogs, fish, lions, humans and locusts do not see the same things as equal in size or similar in shape; rather, what they see depends upon the kind of imprinting produced in each case by the eye which receives what is apparent.31

26 Aristotle, De Anima, trans. Christopher Shields (Oxford: Clarendon Press, 2016), 2.6.418a14–15. 27 Luzzatto, Socrates, 9 7. 28 On mirrors, see Jurgis Baltrušaitis, Le miroir: Essai sur une légende scientifique (Paris: Elmayan, 1978); and Richard Gregory, Mirrors in Mind (London: Penguin, 1997). 29 See Faye Tudor, “‘All in Him Selfe as in a Glass He Sees’: Mirrors and Vision in the Renaissance,” in Renaissance Theories of Vision, ed. John Hendrix and Charles H. Carman (Franham: Ashgate, 2010), 171–86. 30 Sextus Empiricus, Outlines of Scepticism 1.40. 31 Sextus Empiricus, 1.48–49. See Diogenes Laertius 9.81, and Annas and Barnes, The Modes of Scep- ticism, 173. 526 The Deceit of the Senses: Sight and the Mirror

Luzzatto imports whole paragraphs from Sextus into his Socrates:

Furthermore, an evident lesson about this distortion of appearances is provided by mirrors, which are generally made of the same matter, but even a small difference in their form may consistently diversify the images reflected in them. Hence, we should consider that images pro- duced by the same object [98] strike different forms of eyes, which are masses of various matters. Therefore, they are reflected, and consequently have very different appearances from that of the object, as their origin and efficient, and also strange dislocations and positions.32

The reason for the difference in reflections cannot be in the object itself, because each reflects the same object. Therefore, one has to infer that the perceived differ- ence depends on the receiver, i. e., the eyes or the reflective surfaces of the mirrors. The images happen to encounter different shapes of eyes or are collected by different materials. For that reason, they are refracted and take on an appearance and shape that differs from the original, with different effects, dislocations, and positions. In this argument, Luzzatto apparently does not realise that the different refractions of the mirror are created by the mirror itself, which is surprising because this problem had already been discussed at length in medieval and humanistic literature,33 and it is difficult to assume that he was unaware of it. However, we have to bear in mind that the Socrates’s scope of discussion seeks to prove the inconsistency of human knowl- edge which comes from the senses. The eye cannot ever be perfectly aware of reality because of its unreliability. The mirror is an example of the unreliability of knowledge that does not affect the object but rather the source of vision itself. I admit that Luzzatto is not clear in his rea- soning, but the use of the mirror cannot obscure the fact that he is speaking of vision and not of lenses for vision. Moreover, seventeenth-century scientists do not address the “errors” of mirrors (de erroribus speculorum) but rather their “fallacies” (de fal- lacia specula), as displayed in the works of Friedrich Risner (1606)34 and Ambrosius Rhodius (1611).35 The change is in perspective; mirrors do not produce “errors,” they are rather a source of fallacies and deceits. The subjects or passive objects of such illusions are clearly the eyes, as Luzzatto continues to maintain at the beginning of his treatise in Socrates’s defence:

Therefore, everything that is perceptible only exists because our mind gives it a form and appear- ance. This complies perfectly with what our Protagoras used to say: that a human being is the measure both of things [that are to the extent that they] appear to him in the world and also of those things which are not to the extent that they do not appear to him. The same [thing] happens to the objects that we apprehend: we wrongly consider our robes and coverings to be

32 Luzzatto, Socrates, 97–98. 33 See Baltrušaitis, Le miroir, 241–59. 34 Friedrich Risner, Opticae libri quatuor ex voto Petri Rami novissimo per Fridericum Risnerum ejus- dem in mathematicis adjutorem olim conscripti (Cassellis: Wesselius, 1606). 35 Ambrosius Rhodius, Optica […] Cui additus est Tractatus De crepvsculis (Wittenberg: Seelfisch, 1611). The Deceit of the Senses: Sight and the Mirror 527

the source of that heat which, on the contrary, derives from ourselves and is merely reflected in them and sent back to us. Hence, we are used to believing, perhaps mistakenly, that those mani- festations of external objects that we see are their true images, while in fact, we are their original cause, since most of them come from us. Furthermore, the objects participate in producing them by ejecting them and sending them back to us, like mirrors that reflect the images of the object in front of them. However, the ejected simulacra differentiate and diversify from one another in accordance with the different conditions, figures, and compositions of these mirrors. Thus, the suspension of judgment, which I considered extremely salutary and favourable to humankind, is now considered pernicious and harmful by others, particularly by my slanderers, since they and I judge it with different mental frameworks.36

But let us return to the mirror example: Luzzatto claims that the fallacy of the eyes can be proven by the fact that animals cannot perceive the fallacious beauty of visual arts (above all, painting). In his words, they are incapable of perceiving the “the agree- ableness of the colour, symmetry, or beauty of bodies” (vaghezza di colori, simetria, & bellezza de’ corpi); this is to be seen as a consequence of the different manner in which their eyes are constructed and not a lack of inner sense (variando dal nostro, nella configuratione, situazione, qualità d’humori, membrane, & nervi, & non già per macamento di senso interno).37 The difference between human and animal perception is of great disadvantage to the human being because, according to Luzzatto, animal perception, imitation, and reproduction of sound testify to their considerable perceptual abilities when com- pared to human musical performances. Evidence can be found in the “the tarantula, a despicable insect, [which] knows the modulation of harmonic sounds,” as well as blackbirds and parrots, which can perfectly learn human songs. According to Luz- zatto, perceiving, observing, and learning the harmony of sounds requires much more than what is needed for simply evaluating the charm of colours and bodily pro- portion. Even the common people perceive the latter (questi da più volgari & plebei ingegni sono osseruati). The Venetian Rabbi defends the superiority of music over the visual arts because the former requires much more learning and ability than the latter. He is clearly com- paring the perception and imitation of music with the perception of images, rather than with the reproduction of images, which is the task of painting and sculpture. For him, the near perfection of the auditory senses of animals proves that they possess an inner sense. The difference between animals and human beings rests only in their

36 Luzzatto, Socrates, 14. 37 Luzzatto, 98. The discussion of the topic of animal perception was popular in Luzzatto’s time because of a general sceptical attitude towards human knowledge, as can be found in Descartes’s speculation on mechanical clockworks (the automata). For a discussion of the “reason of the animal,” see the very useful anthology of texts collected by Hans-Peter Schütt, Die Vernuft der Tiere (Frank- furt: Keip, 1990); and Richard Sorabji, Animal Minds and Human Morals: The Origins of the Western Debate (London: Duckworth, 1993). The topic is a desideratum for Judaic studies; for a first (theologi- cal) approach, see Andrew Linzey and Dan Cohn-Sherbok, After Noah: Animals and the Liberation of Theology (London: Mowbray, 1997). 528 The Deceit of the Senses: Sight and the Mirror perception of images and not in the perception and imitation of sounds. This is a means for claiming that animals’ faculties of sight are superior to those of humans, because animals cannot be deceived by any illusion and fraud of painting, as we mere humans often are. Luzzatto attributes animals’ greater ability to perceive the fiction of perspectives and fictive remote distances to the perfection of their visual faculties. To sustain his theory, Luzzatto speaks of a miracle, retelling the well-known episode of a bird, deceived by a painting, that wanted to peck a cluster of grapes.38 Luzzatto believes that the “miracle” happened not because of the perfection of the picture, but because the natural perfection of the bird’s inborn visual faculty was impaired. For “the perfection of their organs defends them from these fallacies” (la perfezione del loro organo li difenda da tali fallacie).39 To understand Luzzatto’s argument, one should keep in mind the ancient, medi- eval, and humanist discussions regarding the property of the mirror and any ani- mal’s capacity or incapacity to cope with it. Since for Luzzatto the source of fallacies is the human eye – not the mirror – he cannot claim that animals can be deceived by mirrors. It is not simply that animal vision is superior to humans, but because a mirror, being only an object, cannot deceive anyone. We can observe here an indirect criticism of magical uses and abuses of the mirror;40 for example, the basilisk’s stare can only be averted by a mirror.41 To accept that mirrors can be sources of error or fallacy, he mentions artistic objects:

What famous painter has ever represented an image so vivid as that which visible objects produce on polished and clear bodies, though they are ruled by simple Nature? What false con- trast of light and dark may be compared with the mirroring and reflection that appear on a mate- rial mirror? However, what increases our astonishment is the rapidity and promptness of their working: the image is represented in the mirror, which accurately reproduces it according to the size and dimension of the object. If by chance the mirror breaks, dividing into minute fragments, in that instant the original – but smaller – simulacrum appears on each small shard, with such symmetry, proportion, and similarity that even the most expert painter, with his instruments, wire grills, compasses, and the expenditure of a long time, would never reach the perfection of such an operation. Likewise, Nature is so sagacious in finding the centre of gravity of bodies that even the most speculative mechanic could never equal it. Indeed, it instantaneously finds the centre of any body, even if is irregular, and this is something that the cleverest intellect may barely achieve with laborious demonstrations.42

The reader is obviously surprised that Luzzatto is returning to the concept of nature even as he regards himself a sceptic. In this respect he is following Sextus, who “attacks such fundamental scientific concepts as time, space, motion, causation,

38 This is an allusion to the story of Zeuxis and Parrhasius; see Pliny the Elder, Natural History 35.36.65–66. 39 Luzzatto, Socrates, 99. 40 On the use of mirrors in magic, see Baltrušaitis, Le miroir, 181–214. 41 Lucan, Pharsalia 9.725–9. 42 Luzzatto, Socrates, 25–26. The Deceit of the Senses: Sight and the Mirror 529 but he never attacks what was, for the Greek thinkers, the central notion of natural science, that of nature itself.”43 Perhaps this is because scepticism is not a system but consists of strategies to demolish dogmatic traditions with dialectic reasoning. Besides, the “nature” used in this quotation consists of facts; indeed, mathematical facts that contain “symmetry, proportion, […] similarity,” and gravity, which accord- ing to Luzzatto cannot be demonstrated. Facts are observable, but the constitution of any science that tries to explain them is necessarily open to criticism.

43 Annas and Barnes, The Modes of Scepticism, 75, with further references.