While the painters were transforming their visual practices, three Florentine thinkers were developing a new theory of seeing – goldsmith and sculptor Lorenzo Ghiberti (1378–1455), architect Filippo Brunelleschi (1337–1446), and priest, architect, artist, and thinker Leon Battista Alberti (1404–1472).

Ghiberti is known for the gilded bronze doors he designed and made in his goldsmith’s shop for the Battistero di San Giovanni in Florence, depicting in relief Old Testament scenes (1425–1452).¹³⁰

On the doors, Ghiberti sized persons according to their distance from the front of the scene. He used architectural settings as a visual framework for three-dimensionality, placing biblical personages against the receding colonnades of buildings and streetscapes that reduce into the distance. For their visual brilliance, Michelangelo called these doors The Gates of Paradise. Ghilberti theorized his art and the art of others in his Commentarii. Of the baptistery doors he said, “I strove to observe every measure of proportion, seeking the closest possible imitation of nature … The figures are relieved against the planes so that the nearer figures appear larger than those further out, just as they are in reality.”¹³¹

Brunelleschi was an architect, designer of the dome of the Duomo in Florence, constructed between 1447 and 1461. The drawings are now lost, but his 1425 demonstration of linear perspective outside the Florence Baptistery is the stuff of legend. According to the West’s self-understanding of its history of imaging, this was the founding moment of realism as technique. Using a canvas with a peephole and a mirror, he showed the diminishing size of the walls of the building the more distant they became. The central point in a hypothetical distance was the “vanishing point,” a centering line of sight oriented to the horizon. The relative sizes of seen objects could be figured mathematically.¹³² Concluded his fellow architect and biographer, Antonio Manetti, this was a crucial contribution to the science of perspective, “setting down properly and rationally the reductions and enlargements of near and distant objects as perceived by the eye.”¹³³

Another architect, Alberti, was the first to theorize the new art and science of imaging in his De Pictura of 1435. Imagine a series of visual rays running from the eye to the objects it sees, he says. “Among these visual rays there is one which is called the centric.” This ray points in the direction of what we know to be the vanishing point of linear perspective. Surrounding this ray, a “visual pyramid” can be conceived, around which objects are arranged “in a definite place in respect to the observer.” Then, to draw, “I inscribe a quadrangle of right angles … which is considered an open window through which I see what I want to paint.” Now, the act of visualization has been moved away from the eye to an intermediate plane, “a thin veil, finely woven, with larger threads [marking out] as many parallels as you prefer. This veil I place between the eye and the thing seen, so the visual pyramid penetrates through the thinness of the veil. This veil … always presents to you the same unchanged plane. Where you have placed certain limits, you quickly find the true cuspid of the pyramid.”

The result is both naturalism and supernaturalism. Naturalism: “the studious painter will know from nature, and he will … be wide awake with his eyes and mind in this investigation and work … discovering and learning beauty.” And still, supernaturalism: “Painting contains a divine force which not only makes absent men present, [and] the dead seem almost alive … [P]ainting is most useful to that piety which joins us to the gods and keeps our souls full of religion.”¹³⁴

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¹³⁰ Richard Krautheimer, 1956, Lorenzo Ghiberti, Princeton, NJ: Princeton University Press.

¹³¹ Lorenzo Ghiberti, c.1447 [1948], The Commentaries, London, UK: Courtald Institute of Art, pp. 24–25; Hans Belting, 2008 [2011], Florence and Baghdad: Renaissance Art and Arab Science, translated by D.L. Schneider, Cambridge, MA: Harvard University Press, pp. 150–54.

¹³² Giulio Carlo Argan, 1946, “The Architecture of Brunelleschi and the Origins of Perspective Theory in the Fifteenth Century,” Journal of the Warburg and Courtauld Institutes 9:96–121; Brian Rotman, 1987, Signifying Nothing: The Semiotics of Zero, Stanford, CA: Stanford University Press, pp. 14–22; Erwin Panofsky, 1924 [1997], Perspective as Symbolic Form, translated by C.S. Wood, New York, NY: Zone Books, pp. 63–64.

¹³³ Hans Belting, 2008 [2011], Florence and Baghdad: Renaissance Art and Arab Science, translated by D.L. Schneider, Cambridge, MA: Harvard University Press, p. 165; Antonio di Tuccio Manetti, 1497 [1970], The Life of Brunelleschi, translated by C. Enggass, University Park, PA: Pennsylvania State University Press.

¹³⁴ Leon Battista Alberti, 1435 [1956], On Painting, translated by J.R. Spencer, New Haven, CT: Yale University Press, pp. 46, 47, 51, 56, 68–69, 92, 63; Michael Baxandall, 1988, Painting and Experience in Fifteenth Century Italy, Oxford, UK: Oxford University Press.

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Cope, Bill, and Mary Kalantzis. 2020. Making Sense: Reference, Agency and Structure in a Grammar of Multimodal Meaning. Cambridge UK: Cambridge University Press, pp. 217–218. https://doi.org/10.1017/9781316459645

Leon Battista Alberti’s "Commentaries" §MS2.2b