História, Ciências, Saúde - Manguinhos ISSN: 0104-5970 [email protected] Fundação Oswaldo Cruz Brasil Edgerton, Samuel Y. Brunelleschi's mirror, Alberti's window, and Galileo's 'perspective tube' História, Ciências, Saúde - Manguinhos, vol. 13, 2006, pp. 151-179 Fundação Oswaldo Cruz Rio de Janeiro, Brasil Available in: http://www.redalyc.org/articulo.oa?id=386137997010 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative BRUNELLESCHI´S MIRROR, ALBERTI´S WINDOW, AND GALILEO´S `PERSPECTIVE TUBE´ EDGERTON, S. Y.: Brunelleschi’s mirror, Alberti’s window, and Galileo’s ‘perspective tube’. História, Ciências, Saúde – Manguinhos, v. 13, (supplement), p. 151-79, October 2006. This essay argues that the advent of linear perspective, ca. 1425, when Filippo Brunelleschi painted a small panel of the Florentine Baptistery by applying the geometric rules of optical mirror reflection, was more than just an artistic event. Indeed, it subsequently had the most profound – and quite unanticipated – influence on the rise of Brunelleschi’s modern science. Surely, by 1609, Galileo would not have understood what he saw when observing the moon through his newly mirror, Alberti’s invented optical telescope, then called the ‘perspective tube,’ had it not been for his training in perspective drawing. Yet, window, and Brunelleschi’s original dependence on the mirror two centuries earlier was intended not Galileo’s to reveal objective ‘scientific’ reality, but rather to reinforce Christian spiritual ‘reality.’ In 1435-6, Leon Battista Alberti, when codifying ‘perspective tube’ Brunelleschi’s perspective in his famous “Treatise on Painting,” substituted a gridded window for Brunelleschi’s mirror, thus redirecting the purpose of perspective art away from revealing God’s divine order as O espelho de reflected on earth, to a more secular physical reality viewed directly in relation to human Brunelleschi, a janela de moral order. KEYWORDS: linear perspective; Renaissance Alberti e o ‘tubo’ de art; modern science. Galileu EDGERTON, S. Y.: O espelho de Brunelleschi, a janela de Alberti e o ‘tubo’ de Galileu. História, Ciências, Saúde – Manguinhos, v. 13, (suplemento), p. 151-79, outubro 2006. O presente ensaio defende que não foi somente um acontecimento artístico o advento da perspectiva linear (c. 1425), quando Filippo Brunelleschi ao pintar um pequeno painel no Batistério Florentino lançou mão das regras geométricas da reflexão em espelho ótico. Esse acontecimento veio a exercer uma profunda e inesperada influência no surgimento da ciência moderna. Com certeza, por volta de 1609, Galileu não teria compreendido o que via quando observava a lua através de seu recém-criado telescópio ótico, então chamado ‘tubo de perspectiva’, se não fosse sua familiaridade com o desenho em perspectiva. No entanto, a original dependência do espelho que Brunelleschi desenvolveu dois séculos antes não almejava revelar uma realidade ‘científica’ objetiva, mas sim reforçar a realidade espiritual cristã. Em 1435-36, Leon Battista Alberti, ao codificar a perspectiva de Brunelleschi em seu famoso ”Tratado de pintura”, substituiu o espelho de Brunelleschi por uma janela gradeada, assim redirecionando o propósito da arte da perspectiva, cujo intuito era não mais a revelação da ordem divina refletida na terra, mas sim de uma Samuel Y. Edgerton realidade física, mais secular, vista diretamente em sua relação com a ordem moral humana. Amos Lawrence Professor of Art History Williams College PALAVRAS-CHAVE: perspectiva linear; arte do Williamstown, Massachusetts – 01267 USA Renascimento; ciência moderna. [email protected] v. 13 (suplemento), p. 151-79, outubrov. 13 2006(suplemento), p. 151-79, outubro 2006 151 SAMUEL Y. EDGERTON igure 1 is an illustration from a sixteenth-century manual on F how to draw a simple picture in linear perspective. Figure 2 shows the twentieth-century rocket-powered Apollo spaceship preparing to drop its Eagle lander on the surface of the moon. In this essay, I argue that the construction of such complex mechanical devices, and even the possibility that the Eagle could stand on such an extraterrestrial body, could never have been realized without the humble artistic technique diagrammed in Figure 1. Indeed, linear perspective for painters, first conceived by the Italian artisan Filippo de Ser Brunelleschi in Florence (1377-1446), was one of the most decisive ideas in the history of Western technology 1 This essay is actually and science as well as art. 1 itself an ‘abstract’ of a new book of the same In the history of technology everywhere in the world, including name I am currently the West, before the fifteenth century, mechanical apparatuses of writing. whatever sort were never constructed from scale plans. Sometimes pictures were used, as in this quite non-perspective drawing from a fourteenth-century Islamic manuscript (Figure 3), but only to suggest the general purpose of the machine (a water pump) so that a skilled artisan, who already knew how to build such devices, could simply be reminded of what he was to construct, with little more than a glance at the image. In any case, it’s obvious that the picture is hardly an accurate diagram-to-scale from which a three- dimensional working model could be fabricated. Look now at Figures 4 and 5. The former is a drawing of a suction pump by an early fifteenth-century Italian engineer called Taccola (1381-ca.1453). He already knows about the new linear perspective, and his scale drawing could indeed be used in order to build from it a three-dimensional working model. But observe again: there’s a flaw evident in this drawing. As the crank at the top turns, the rope that pulls the piston up and down must oscillate back and forth with every turn, causing the piston to rub each side of the circular wellhead until it is eventually bent into the shape of an oval, and thus cause the pump to loose suction and become dysfunctional! What’s interesting is that this pump never needed to be built in order to prove, at expensive cost, that it would indeed quickly fail. Taccola’s successor, the great Italian engineer, architect, and painter, Francesco di Giorgio Martini (1439-1501), realized the flaw instantly, simply from studying this earlier drawing. Without even having to reconstruct a model of the old pump in order to test its oscillating 2 For more on the action, he was able to redesign it with an ingenious, correcting Italian (Sienese) improvement. Notice that the crank in his, the latter Figure 5, now engineers, Taccola and Francesco di has a rolling slip ring around it, and the piston rod has a loop in Giorgio Martini, see the top in which the slip ring can roll back and forth so the piston my earlier book: Edgerton, 1991, p. only goes straight up and down, and never wobbles, thus causing 125-39. no damaging friction.2 152 História, Ciências, Saúde – Manguinhos, Rio de Janeiro BRUNELLESCHI´S MIRROR, ALBERTI´S WINDOW, AND GALILEO´S `PERSPECTIVE TUBE´ Figure 1 Figure 2 v. 13 (suplemento), p. 151-79, outubro 2006 153 SAMUEL Y. EDGERTON Figure 3 154 História, Ciências, Saúde – Manguinhos, Rio de Janeiro BRUNELLESCHI´S MIRROR, ALBERTI´S WINDOW, AND GALILEO´S `PERSPECTIVE TUBE´ Figure 4 v. 13 (suplemento), p. 151-79, outubro 2006 155 SAMUEL Y. EDGERTON Figure 5 156 História, Ciências, Saúde – Manguinhos, Rio de Janeiro BRUNELLESCHI´S MIRROR, ALBERTI´S WINDOW, AND GALILEO´S `PERSPECTIVE TUBE´ These simple drawings, dependent as they were on the draftsmen’s knowledge of linear perspective to scale, indicate graphically what this unique Renaissance art technique bequeathed to modern technology, and even to modern science, as I shall show an amazing example of shortly. To repeat, linear perspective drawing to scale made it possible to invent, improve, and correct the most complex machinery without having to waste time and money building and testing actual three-dimensional models. No rocket ship to the moon could ever have been invented, let alone be built, without the humble heritage of Renaissance linear perspective. The rest of my essay will now be devoted to how that remarkable and unexpected relationship came about. Indeed, as we shall now see, linear perspective was first devised with no such scientific application in mind, but solely to help solve a very medieval theological problem, the burgeoning feeling among many intellectuals of the late Middle Ages that the traditional styles of religious painting no longer inspired the faithful sufficiently, especially during a gloomy time when the Holy Mother Church was suffering a number of traumatic crises like the loss of Jerusalem and the failure of the Christian Crusades, the terrible Schism of Church itself, and the even more terrible onset of the Black Death in the fourteenth century. In these miserable times, many people thought that God had abandoned them. What was needed in order to restore the faith, many community leaders and churchmen felt, was to make people feel that God and his saints were once more immanent in their daily lives, Figure 6 and that people could see and touch them just as if they were actual life-size persons in the here and now. Even figuratively putting their fingers in Jesus’ wounds – just as Saint Thomas did – in a famous Florentine statue, so illustrative of this famous Biblical proof (Figure 6), by the sculptor, Andrea del Verrocchio (ca.1435-1488), teacher of Leonardo da Vinci and whose surname, by the way, means ‘True Eye.’ Ironically, the currently popular early fifteenth- century “International Style” of painting, even religious painting as displayed in v. 13 (suplemento), p. 151-79, outubro 2006 157 SAMUEL Y. EDGERTON churches, was anything but inspirational.