History of optics

Este capítulo está dedicado a las fuentes ópticas de Leonardo da Vinci, que pueden haber contribuido a su conocimiento y a su pericia práctica de la perspectiva.
Para estudiar las fuentes de Leonardo, aplicaré el "método de los trazadores", un refinamiento del estudio de los paralelismos textuales que consiste en: 1/ establecer la comparación en palabras de baja frecuencia léxica; 2/ extender la contraposición de los textos emparentados al mayor número de textos posible. Consideraré tres casos: las fuentes vinculadas a un nombre de autor, las fuentes no vinculadas a un nombre de autor y las fuentes sin paralelismo textual.

En 1623 el cordobés Benito Daza de Valdés publica el libro "Uso de los Antojos", un tratado sobre óptica oftálmica en el que se ensalza la corrección de problemas visuales refractivos mediante el uso de lentes cóncavas o convexas, en función del defecto que se padezca. Las aportaciones de este tratado, primero en su género en el mundo, son tan importantes como el concepto de "grado", equivalente a la dioptría de hoy, el orificio estenopeico en ciertas gafas, el sistema de graduación ocular o la identificación de la hipermetropía. En él se añade también un capítulo dedicado a los telescopios o catalejos de su época, con descripción y clasificación de los mismos.

L’analisi dei paralleli testuali mediante «parole traccianti» consente precisare le idee di Werner, Björnbo, Vogl, Lindberg e Federici Vescovini sull’eredità latina di al-Kindi. Presa l’eredità nel senso lato di influenza, qualunque siano gli intermediari di diffusione, si può affermare che al-Kindi ha influenzato lo sviluppo dell’ottica e della prospettiva nell’Europa medievale e rinascimentale. Presa l’eredità nel senso stretto di conoscenza diretta dell’ottica di al-Kindi, viene dimostrato che molti temi alkindiani furono conosciuti soltanto attraverso fonti secondarie.

Resumo: A mais antiga obra sobre Óptica Geométrica que chegou até nós é atribuída a Euclides (aproximadamente 300 a.C.). Nesse tratado, Euclides utiliza a hipótese de raios visuais emitidos pelos olhos e analisa principalmente a aparência visual de objetos, estudando seus tamanhos aparentes (ângulos visuais) e posições. Este artigo apresenta primeiramente uma visão geral sobre a natureza da Óptica Geométrica na Antiguidade grega, sem abordar os fenômenos de reflexão e refração, estudando várias aplicações do princípio de propagação retilínea da luz ou da visão. Depois, o artigo aborda a Optika de Euclides, apresentando sua transmissão histórica, as várias versões existentes, as discussões sobre autoria da obra e outros aspectos historiográficos. Por fim, o artigo apresenta uma análise de todo o conteúdo da Optika. Palavras-chave: Euclides; óptica geométrica; história da óptica; óptica na Antiguidade

From ubiquitous surveillance to drone strikes that put “warheads onto foreheads,” we live in a world of globalized, individualized targeting. The perils are great. In The Eye of War, Antoine Bousquet provides both a sweeping historical overview of military perception technologies and a disquieting lens on a world that is, increasingly, one in which anything or anyone that can be perceived can be destroyed—in which to see is to destroy.

Arguing that modern-day global targeting is dissolving the conventionally bounded spaces of armed conflict, Bousquet shows that over several centuries, a logistical order of militarized perception has come into ascendancy, bringing perception and annihilation into ever-closer alignment. The efforts deployed to evade this deadly visibility have correspondingly intensified, yielding practices of radical concealment that presage a wholesale disappearance of the customary space of the battlefield. Beginning with the Renaissance’s fateful discovery of linear perspective, The Eye of War discloses the entanglement of the sciences and techniques of perception, representation, and localization in the modern era amid the perpetual quest for military superiority. In a survey that ranges from the telescope, aerial photograph, and gridded map to radar, digital imaging, and the geographic information system, Bousquet shows how successive technological systems have profoundly shaped the history of warfare and the experience of soldiering.

A work of grand historical sweep and remarkable analytical power, The Eye of War explores the implications of militarized perception for the character of war in the twenty-first century and the place of human subjects within its increasingly technical armature.

Introduction At present our historical studies of Renaissance color philosophy and science resembles the pieces of a mosaic, only some of which have been assembled to form a larger picture. The task is difficult: the sixteenth century saw an explosion in Aristotelian commentaries and textbooks, most of which have not been carefully examined by modern scholars. The medical tradition saw a similar deluge in printed works, including new commentaries on Avicenna, the revival of Hippocratic and Galenic medicine and philosophy, the ascendency of the discipline of anatomy, and new challenges to traditional medicine – all of which were opportunities for reexamining the importance of color in health, disease, theories of complexion and the four humors, anatomy, and natural processes generally. New philosophical systems came to the fore, notably the alchemical philosophies inspired by Paracelsus; the Neoplatonic, Hermetic, and magical directions inspired by Marsilio Ficino and others; the revival of ancient Scepticism; the Christianized Epicureanism of figures such as Pierre Gassendi; and eclectic philosophies that combined Aristotelian, Stoic, Platonic, and Hermetic, ideas with Renaissance animism – often, as in Bernardino Telesio or Francis Bacon, cast as anti-Aristotelian philosophy. The European conception of the natural world affected by the projects of exploration and colonization, and devising new methods of getting a handle on this wealth of new information became paramount. The science of mechanics developed dramatically, and during the first half of the seventeenth century the mechanical philosophy was ascendant, effecting radical changes to the notions of density, rarity, transparency, and opacity – concepts that were fundamental to how color was theorized. The status of painters and painting rose significantly. Intellectual reflections on painting, including color, became common, both because training in drawing and painting became widespread among the learned, and because painters themselves entered the orbit of the litterati. Mining and minerology was increasingly important in Europe, and works (such as Georg Agricola's De re metallica) on metals, stones, and gems were written that combined the philosophical and the practical (see chapter 10). The increasing popularity of Kunstkammer, or cabinets of curiosity, offered a new locus for knowledge transfer among different groups. The science of optics was, moreover, transformed by advances in ocular anatomy together with the quest to mathematically comprehend devices such as the telescope and camera obscura; alongside this, philosophers began to rethink what the act of seeing entails. For all of the above, particularly its relevance to color, our current knowledge is incomplete. One way to make sense of these myriad changes is to focus on the fact that the color worlds – consisting of practices, concepts (including language), and objects – of various artisans and intellectuals began to overlap during this period, with major consequences for philosophical and scientific reflections about color (Baker et al, 2016). Social and disciplinary boundaries became increasingly porous, even while many disciplines themselves underwent transformations.

This is an excerpt from Rediscovering Optics, Minneapolis: BENA Press, 1992. The book is available at Amazon.com:
http://www.amazon.com/Rediscovering-Optics-Science-Nahum-Kipnis/dp/096367840X/ref=sr_1_1?s=books&ie=UTF8&qid=1422923574&sr=1-1&keywords=rediscovering+optics
This book is for science teachers and advanced students.  It shows how to teach optical concepts by  viewing them at the time of their discovery and relying on students' reproduction of historical experiments. A digital version (pdf) is available, inquire at the author.

This paper deals with the debate between A. Mark Smith and David C. Lindberg on the Big picture of medieval optics as perspectiva. A. Mark Smith argued that medieval optics was cognitive science in the modern sense, yet Lindberg expressed a reserved position that Smith's argument be acceptable only to a certain extent. In order to contextualize this debate historically, the paper has examined the accounts of medieval theorist, Robertus Grosseteste, Johannes Peckham and Dominicus de Clivaxo, and presented the modern translation for perspectiva. Furthermore, the paper pointed out that widespread interpretation of medieval optics is anachronistic, revealing its mere prejudices of medieval optics.

Doktora Tezi / Doctoral Thesis

Bu çalışma, kelam düşüncesinde yer verilen bilimsel bilgi ve kelamın bilim ile kurduğu ilişkiyi ele almaktadır. Kelamcılar, kelamın teşekkülü ile birlikte bilim tarihi açısından bilim olarak kabul edilen alanlarla ilişki kurmuş, kelam eserlerinde bu bilgi türüne benimseme ya da eleştiri bağlamında yer vermiştir. Allah’ın görülmesinin imkanının tartışıldığı rü’yetullah meselesi, görme duyumunun teorik açıklamasını içermesi bağlamında kelamcıların bilimin araştırma alanına giren görme konusundaki yaklaşımları üzerinden kelam-bilim ilişkisini incelemeye müsait bir konudur.

Çalışma iki bölümden oluşmaktadır. Birinci bölümde rü’yetullah konusu, problemin tarihsel sürecinden başlamak üzere, erken dönem Mu‘tezile Eş‘arîyye ve Mâtürîdîyye kelamındaki tartışmalar çerçevesinde ortaya konulmuştur. Bu çerçevede Allah’ın görülemeyeceği ve görülebileceği iddialarının akli ve nakli delilleri ele alınmış, zaman ve mekan açısından Allah’ın görülmesinin tartışıldığı bağlamlar ayrıca incelenmiştir. İkinci bölümde rü’yetullah tartışmaları sebebiyle kelam içerisinde yer alan bilim olarak görme duyumunun teorisi tespit edilmiştir. Bu çerçevede kelamcıların görmenin gerçekleşebilmesi için gerekli olan şartlar, görme süreci, görmenin gerçekleşme biçimi, görmeyi engelleyen problemler ve nelerin görülebileceği konularındaki yaklaşımları incelenmiştir. Kelamcıların bilimsel bilgi ile kurduğu ilişki ise, görme olgusu çerçevesinde teolojinin bilimsel açıklamayı belirlemesi ve bilimsel açıklamanın teolojiyi belirlemesinin örnekleri üzerinden açıklanmıştır. Son olarak kelamcıların görme konusundaki temel iddialarının güncel bilim açısından değerlendirmesi yapılmıştır.

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In this doctoral thesis, the scientific knowledge in Islamic theology (Kalām) and the relationship between theology and science has been studied. Islamic theologians (Mutakallimūn), with the formation of Kalām, established relations with the fields categorized as science in terms of the history of science, and included parts of this knowledge in their books. Vision of God (Ruʿyat Allāh) issue is a suitable subject for examining the Kalām-science relationship because of Mutakallimūn’s investigation of the theoretical explanation of the sense of sight within the subject.

This study consists of two chapters. In the first chapter, the subject of Ruʿyat Allāh is portrayed within the framework of the discussions in the early Muʿtazilah, Ashʿariya and and Māturīdīyah Kalām, starting with the history of the problem. The proofs of Mutakallimūn about whether Ruʿyat Allāh is possible or not are discussed and various aspects of the issue in terms of time and place are also scrutinized. In the second chapter, Mutakallimūn’s theory of vision, which is the science within Kalām due to the problem of Ruʿyat Allāh, is unveiled. In this context, assumptions of Mutakallimūn about the conditions necessary for seeing, the mechanism of seeing, the problems that prevent seeing and what can be seen are examined. The relationship between Kalām and scientific knowledge is explained through examples of theology's determination of scientific explanation and the scientific explanation's determination of theology within the framework of sight. Lastly, principal claims of the Mutakallimūn about vision are evaluated in terms of contemporary science.

The seventeenth century saw radical changes to theories of vision, light, color, matter, and knowledge about animal bodies. Understanding vision in the sixteenth century is essential to grasp these changes, but here many lacunae exist. Histories of vision have focused on mathematical optics and neglected color in natural philosophy and medicine. Historians of medicine have not sufficiently analyzed works on vision and color by physicians. Finally, historians of philosophy have produced few analyses of color theory from antiquity until 1600.

My dissertation analyzes two highly important works on vision that have yet to be examined in detail by modern scholars: the natural philosopher Jacopo Zabarella's De visu, first published in his natural philosophy textbook De rebus naturalibus in 1590, and the physician and anatomist Hieronymus Fabricius ab Aquapendente's De visione, first published in 1600. Both taught at the University of Padua, at the time Europe's most prestigious medical school, and their stature and influence was considerable.

Chapter 1 provides the history of one widely held theory of what color is and how it arises, which I dub the condensation theory of the origin of color. This theory arises from the Aristotelian commentary tradition with significant influences from astronomy, optics, and anatomy. This theory of color was closely intertwined with an Aristotelian cosmology, and is found in fully developed form in Averroës. Chapter 2 analyzes book 1 of Zabarella's De visu, where we find the most rigorous and complete explication of this theory in its history. Chapter 3 is an analysis of Fabricius's De visione, which combines anatomy, natural philosophy, and mathematical optics. Chapter 4 examines the shared, novel theory of vision held by Zabarella and Fabricius, and argues that they interacted across disciplinary lines in forming it. Chapter 5 demonstrates Zabarella’s and Fabricius’s influence on highly important figures for seventeenth-century optics and visual theory, such as Johannes Kepler, François Aguilón, and Christoph Scheiner; it argues for a revision to current narratives about the reception of the retinal theory of vision; and it addresses some major misconceptions about transformations to theories of vision and sensation in the seventeenth century.

Since the nineteenth century, much research has been published in various languages about Ibn al-Haytham and his works in optics and mathematics. Since then, we have found in the writings of scholars that he has had extensive knowledge and works in several fields of philosophical, natural and mathematical sciences. In addition to his famous writings on optics and his research in mathematics, he has been the author of numerous works on the interpretation of philosophy, logic, and natural sciences in the Aristotelian and Galenic traditions. Some works about the history of Islamic philosophy emphasize the philosophical dimension of his thought and by highlighting it, Ibn al-Haytham has been introduced as a comprehensive philosopher who has also contributed to optics and mathematics.
By looking at Ibn al-Haytham's works, we come across a long list of philosophical and mathematical writings. Professor Roshdi Rashed has reached this conclusion in his research: We are actually dealing with two different persons named Ibn al-Haytham: Al-Ḥasan ibn al-Haytham, a mathematician, with famous and accurate works in the fields of mathematics including optics and the astronomy, and Muhammad ibn al-Haytham, a philosopher, with works on the interpretation of the traditional Alexandrian philosophical tradition (Aristotelian, Neoplatonic, Stoic) and more, with the aim of facilitating the teaching of these works to those interested in philosophical studies. The distinction of these two Ibn al-Haythams and the recognition of the two from each other bears fruits in the study of the history of science which leads us to deal with the arguments of Rashed in this regard. In this article, by referring to Roshdi Rashed's textual studies and some others, a total of twenty pieces of evidence have been shown to distinguish between these two Ibn al-Haythams.

Tutto quello che sappiamo della vita di Ibn al-Haytham viene dai racconti dei quattro bio-bibliografi Ṣāʿid al-Andalusī, al-Bayhaqī, Ibn al-Qifṭī e Ibn Abī Uṣaybiʿa (Sabra 1989, II: xix-xxiv; Rashed 1993: 1–19)… Ibn al-Haytham non morì nel 1039, come si scrive, ma dopo 432 dell’Egira (dal 11 settembre 1040 al 30 agosto 1041) perché Ibn al-Qifṭī afferma che «possedeva un volume (juzʾ) di geometria scritto dalla mano di Ibn al- Haytham e datato 432» (Ibn al-Qifṭī ed. Lippert 1903: 167).

Una nota dello storico bizantino Giovanni Tzetzes ci permette di datare la nascita di Archimede, figlio dell'astronomo Fidia, circa 287 a.C. La tesi, sostenuta da Clagett, che avrebbe studiato ad Alessandria prima di tornare in Sicilia, deve essere abbandonata perché non ci sono prove che Eratostene, Conone e Dositeo, a cui Archimede dedica i suoi trattati, vivessero in Egitto.

PREFACE
This book is a historical-epistemological study of one of the most consequential breakthroughs in the history of celestial mechanics: Robert Hooke's (1635-1703) proposal to "compoun[d] the celestial motions of the planets of a direct motion by the tangent & an attractive motion towards a central body."  This is the challenge Hooke presented to Isaac Newton (1642-1727) in a short but intense correspondence in the winter of 1679-80, which set Newton on course for his 1687 Principia, transforming the very concept of "the planetary heavens" in the process.
It is difficult to overstate the novelty of Hooke's Programme.  The celestial motions, it suggested, those proverbial symbols of stability and immutability, were in fact a process of continuous change: a deflection of the planets from original rectilinear paths by "a centrall attractive power." There was nothing necessary or essential in the shape of planetary orbits, and as Newton was quick to realize, this also implied that "the planets neither move exactly in ellipse nor revolve twice in the same orbit, so that there are as many orbits to a planet as it has revolutions." Far from "being exceedingly well ordered in heaven," as Kepler was still very much certain they were, the planetary trajectories, according to Hooke's Programme, represented nothing but a precarious balance between conflicting tendencies.
Culminating in this paragon of abstract celestial mechanics, however, the traces of Hooke's construction of his Programme lead through his investigations in such practical, earthly disciplines as microscopy, practical optics and horology. Similarly, the mathematical tools Newton developed torealize Hooke's Programme appear no less crafted and goal-oriented than Hooke's lenses and springs. This transgression of the boundaries between the theoretical, experimental and technological realms lends philosophical significance to Hooke's free excursions in and out of the circles occupied by gentlemen-philosophers, university mathematicians, instrument makers, technicians and servants. Tracking these forays thus becomes more than just a survey of the epistemic activities of late seventeenth century English savants. Rather, it presents an opportunity to examine the epistemological categories embodied by Hooke and Newton, and the suspicion that much of these categories is nothing but a reflection of the social divisions, relations and hierarchies that separated Hooke's diverse acquaintances and collaborators.

From its foundation in 1348, the University of Prague attracted students as well asscholars from all over Europe to its Faculty of Arts, where they studied and taught the subjects of the curriculum in all their variety. Nevertheless, our knowledge about these Prague scholars and their thought is still rather limited. In an effort to fill this gap, this volume is the first devoted entirely to the production, reception, and transmission of knowledge in the Arts Faculty of the medieval University of Prague, covering topics in astronomy, linguistics, logic, metaphysics, meteorology, and optics. It also links Prague's Faculty of Arts to several others at universities across Europe and it examines the study of the arts in Bohemia outside the university, including the Jewish milieu. The book contributes to advancing the status quaestionis in various ways, mainly through the analysis of less well-known and even unpublished texts, critical editions of some of which are printed here for the first time.

257 pp. Bardwell Press – Why did linear perspective rise in Trecento-Quattrocento Central Italy rather than in any other cultural context? This book provides new insight into the question of the early Italian pioneership in perspective, building on the fact that many references to optics are found in Renaissance perspective treatises. The fact that most of the medieval optical manuscripts were written by masters suggests a closer look at the functioning of medieval universities (studia generalia). An in-depth study of recruitment highlights the exceptional mobility of master and lectors throughout Europe.It is shown that, during the thirteenth and fourteenth centuries, the nearer a university was to Central Italy, the more cosmopolitan it was. Through the masters' mobility, knowledge circulating in the network preferentially flowed into Central Italy.
This study combines a broad spectrum of methods, ranging from the biography of university staff to textual parallels inquiry, from cross-cultural comparisons to advanced network analysis and modelling.

The optical instruments developed through the seventeenth century allowed peering into the very far and the very small; a spectacle never before experienced. The telescope, and later the microscope, was now expected to answer fundamental questions and resolve cosmological riddles by direct observation into the foundations of nature. But this ability came at an unexpected price and with unexpected results. For Kepler and Galileo, the new instruments did not offer extension and improvement to the senses; they replaced them altogether. To rely on their authority was to admit that the human eye is nothing but an instrument, and a flawed one at that. Rather than the intellect's window to the world, the human senses became a part of this world, a source of obscure and unreliable data, demanding uncertain deciphering. Accurate scientific observation meant that we are always wrong.

Inúmeros autores têm contribuído, ao longo dos séculos, para a instauração de um mito em torno da personalidade de Leonardo da Vinci, intensificando de sobremaneira uma percepção desviante da sua verdade histórica. Paul Valéry constitui um desses casos, ao considerar que Leonardo ocupa um solitário papel na laboriosa dissecação da machina do mundo que ao longo dos séculos XV e XVI constituiu as fundações da idade moderna e do habitual equivoco historicista apelidado de “Renascimento”. Na sua Introdução ao Método de Leonardo da Vinci, Valéry prefigura o cúmulo de alguém, que face à natureza equívoca da personagem, sucumbe a uma hiperbólica caracterização das suas obras: “Alguns trabalhos de índole científica, por exemplo, e muito especialmente os de matemática, apresentam uma tal limpidez de organização que até parecem obra de ninguém. São algo de inumano” (Valéry, 2005, pp. 13 - 16). Acontece, na verdade, que os textos consagrados por Leonardo à matemática, ocupam uma ínfima parte de todo o corpus tratadístico que produziu e limitam-se a emular questões amplamente debatidas nos círculos de erudição coetâneos. Confrontado com este flagrante desvio à verdade histórica, André Chastel fala da criação de um «mito Leonardiano» de contornos claramente esotéricos e Freudianos como modo de conferir a uma subtil e evasiva personalidade artística, a consistência e a coerência dos heróis novelescos. Será esta a génese, na sua opinião, daquilo que classifica como os diversos desenvolvimentos naïfs da lenda de Leonardo: o mago; o necromante; o sábio que tudo antecipa; o técnico que tudo realiza; o artista maldito, etc. (Vinci, 1987, p. 5). O equivoco mais habitual, refere-se precisamente ao facto de Leonardo, dotado de um espírito inquisitivo único na história da humanidade, ter constituído o principal motor do renascimento e da subsequente revolução científica. Esta flagrante ausência de todo e qualquer enquadramento prévio capaz de o explicar do ponto de vista de uma fenomenologia cultural, isola o homem histórico do seu próprio vínculo cronológico; mais, isola-o da sua própria humanidade, tornando sobrenatural um fenómeno perfeitamente inteligível no seu lapso vivencial.

261 pp. Springer (Sources and Studies in the History of Mathematics) – This book provides the critical edition of Ibn al-Haytham’s On the Shape of the Eclipse with English translation and commentary, which records the first scientific analysis of the camera obscura. On the Shape of the Eclipse includes pioneering research on the conditions of formation of the image, in a time deemed to be committed to aniconism. It also provides an early attempt to merge the two branches of Ancient optics—the theory of light and theory of vision.
What perhaps most strongly characterizes this treatise is the close interaction of a geometric analysis of light and experimental reasoning. Ibn al-Haytham conducted his experiments in a systematic way by varying all that could be changed: the shape and size of the aperture, the focal length of the camera obscura, the distance and shape of the celestial bodies. This way, he achieved a thorough understanding. This work represents a decisive step in both the history of optics and the application of the experimental method that was just as efficient in medieval Islam as today.

Stephen Toulmin, in an introductory text on the philosophy of science, once remarked that science entails a new way of looking at old or familiar phenomena. If this characterization is accurate and I think that it is, then NicholasAllen's text on what is traditionally referred to as the Shroud of Turin is an admirable account of doing science by dispensing with worn out, unsatisfactory explanations and taking a new look at the phenomenon in question.
And if this new look involves the application of something else, in this case the familiar principles of photography, then the latter may equally be illuminated in new, unexpected ways which invite a surprising rethinking of orthodox accounts of the history of art, science and technology.At the same time, ProfAllen's hypothesis, the elegant simplicity of which is matched only by the persuasiveness of its explanatory power, is a salutary reminder that Western science and technologymay not be all that we have traditionally been led to believe.
His work on the origin of the Shroud suggests, instead, that what most people have always regarded as the exclusive achievements ofWestern culture, may in fact have some of its important roots in some other knowledge tradition, from which it was appropriated by virtue of some set of historical circumstances.
In this respect Allen's research is related to the work of those scholars such as Sandra Harding who have put forward arguments and adduced evidence that (`Western') science may in fact be a multicultural phenomenon. Regardless of its contribution to the recovery of `lost' knowledge and technology, however,Allen's argument is a splendid instance of the structure of scientific research in the form of an interplay between what Popper called `conjecture and refutation' (and, of course, confirmation).

Every step of the way the reader witnesses the emergence of conjectural hypotheses that are continually subjected to scrutiny in the light of guiding theoretical assumptions as well as (corroborating or falsifying) evidence. ProfAllen's ability to formulate alternative, increasingly more accommodating explanations at every turn, bears witness to the breadth of his erudition and the depth of his insight.
I shall refrain from spoiling the fun of discovery on the part of prospective readers by letting the cat out of the bag, so to speak, concerning the specifics ofAllen's hypothesis on the way the Shroud of Turin was made. Suffice it to say that it provides the most tenable account to date, as may be gathered from the fact that ProfAllen has even succeeded in making a Port Elizabethan counterpart to the Turin artefact by implementing the scientific technological principles and procedures which he believes to have been used to create the original Shroud. I am convinced that open minded readers of his book will not be disappointed.
Prof Bert Olivier Department of Philosophy University of Port Elizabeth 1997

Resumo: Este artigo apresenta o desenvolvimento da Óptica – especialmente sob o ponto de vista da teoria da visão – da Antiguidade até o período medieval, indicando a importância do trabalho de Ibn al-Haytham no desenvolvimento de novas ideias que transformaram essa teoria. No século XI, Ibn al-Haytham introduziu uma interpretação que é parcialmente igual à que aceitamos hoje: a de que a visão ocorre quando a luz atinge os objetos e, depois, é captada por nossos olhos, produzindo neles imagens. Porém, a compreensão do funcionamento dos olhos só se deu, de fato, no século XVII, culminando com a contribuição de Kepler. É necessário perceber a importância da contribuição de al-Haytham, mas também é extremamente relevante captar as limitações de sua teoria, sem descrevê-la de modo anacrônico.
Palavras-chave: história da Óptica; história da Física; teoria da visão; Ibn al-Haytham; Óptica medieval; ciência islâmica

For a reassessment of Della Porta’s optics a broad view is needed. For a better understanding of the similarities and the peculiarities of Della Porta’s approach in comparison with other authors of the same period, we are going to deal with Maurolico as one of the best candidates.

The article focuses on the influence exerted by Cornelius Agrippa of Nettesheim in the explanation of the ghostly apparitions provided by Giulio Cesare Vanini. Moreover, the interpretation of Agrippa as an atheist, proposed by Vanini, is examined.

Giovanni Pecham (Peccam, Peckam, Peckham), nato intorno al 1225 a Patcham (Sussex) entrò nell’ordine francescano (Ordo Fratrum Minorum) in una data sconosciuta intorno al 1250–6. Fu mandato allo studium di Parigi per studiare teologia (1257–9). Pecham probabilmente rimase a Parigi fino al 1272, dove poté incontrare Ruggero Bacone, che risiedeva lì tra 1257 e 1267 o 1280 (Lindberg 1976: 117). Alla fine di questo periodo, divenne magister regens dello studium parigino (1269–71) prima di essere nominato l’undicesimo lettore a Oxford (1272–4). Alcuni anni dopo, ottene il carico di lettore presso il Sacro Palazzo (1277–9), poi tornò in Inghilterra, essendo nominato arcivescovo di Canterbury (1279–92) (Boureau 2002; Etzkorn 2011). Pecham, che probabilmente era

Ruggero Bacone (ca. 1220-ca. 1292) nacque a Ilchester, nel Sommersetshire, in una data sconosciuta intorno al 1214, o più probabilmente 1220. Bacone ha studiato a Oxford (1234-42) prima di andare a Parigi, dove diviene maestro d'arte nel 1242 ed insegna subito dopo la filosofia di Aristotele. Ritornato a Oxford tra il 1248 e il 1251, abbandona la filosofia di «studio e commento» per dedicarsi allo studio della scienza sperimentale-una svolta decisiva che potrebbe essere spiegata dalla sua introduzione nell'ambiente di Roberto Grossatesta e del sue discepolo Adam de Marisco, magister regens dello studium di Oxford (vedi Oliver 2004). Dopo dieci anni di studi di matematica, ottica e astronomia, Bacone entrò nell'ordine francescano nel 1257 a Parigi, dove rimase fino al 1279. Ostacolato all'interno dell'ordine a causa della sua indipendenza di pensiero, chiese protezione al cardinale Guy de Foulques, nel frattempo eletto papa Clemente IV, che nel 1266 dimostrò interesse nella sua opera chiedendogli di inviare i suoi scritti. L'Opus tertium ci informa che, verso il 1267, un allievo di Bacone di nome Johannes [da Londra?] portò al papa l'Opus maius, l'Opus minus, il De multiplicatione specierum, il De speculis comburentibus nonché una lente ottica: «Puer vero Johannes portavit crystallinum sphericum ad experiendum» (Bacone ed. Brewer 1859: 111). Il poco tempo tra l'incarico e l'invio suggerisce che Bacone abbia iniziato a scrivere il suo lavoro molto prima, forse all'inizio degli anni 1260. La morte di Clemente IV nel 1268 pose fine alle sue speranze di vedere un rinnovamento del sapere umano mediante la scienza sperimentale. Il generale francescano Girolamo d'Ascoli ordinò persino che fosse posto sotto vigilanza verso il 1277-8, propter quasdam novitates suspectas. Ruggero Bacone tornò a Oxford intorno al 1280, dove morì nel 1292 o poco dopo (Lindberg 1983; Hackett 1997). L'ottica di Bacone è caratteristica delle dottrine del Medioevo latino: offre una sintesi del rinnovamento scientifico dovuto alle traduzioni dell'arabo-in particolare dall'ottica di Alhacen-e dell'impegno sperimentale promosso da Grossatesta a Oxford (Lindberg 1976: 107-116). Si nota anzitutto l'importanza del tema della multiplicatio specierum, destinata a diventare un topos dell'ottica del XIV secolo.