Excerpts from
Brunelleschi's Dome: How a Renaissance Genius
Reinvented Architecture (2000)
by Ross King
By 1418 Filippo [Brunelleschi] was probably best known for an experiment in linear perspective. This experiment must have been conducted in or before 1413 when Domenico da Prato refers to him as "the perspective expert, ingenious man, Filippo di Ser Brunellesco, remarkable for skill and fame." It was one of the first of Filippo's many innovations and a landmark in the history of painting.
Perspective is the method of representing three-dimensional objects in recession on a two-dimensional surface in order to give the same impression of relative position, size, or distance as the actual objects do when viewed from a particular point. Filippo is generally regarded as its inventor, the one who discovered (or rediscovered) its mathematical laws. For example, he worked out the principle of the vanishing point, which was known to the Greeks and Romans but, like so much other knowledge, had long since been lost. Greek vase paintings and marble reliefs show an understanding of perspective, as do some of the scene paintings for Greek tragedies staged in Athens . . . The Romans made use of perspective in their wall paintings, and some of its principles were described by the architect Vitruvius. Furthermore, its seems inconceivable that building such as the Pantheon or the Colosseum could have been built without their architects executing perspective drawings of some sort.
After the decline of the Roman Empire, however, the technique of perspective drawing was lost or abandoned. Plato had condemned perspective as a deceit . . . This prejudice against the "dishonesty" of perspective was adopted in Christian art, with the result that naturalistic space was renounced throughout the Middle Ages. Only in the first decades of the fourteenth century did the ancient methods of perspective reappear when Giotto began using chiaroscuro--a treatment of light and shade--to create realistic three-dimensional effects.
Filippo might have seen examples of ancient perspective painting during his travels through Italy. But he probably worked out the principles of perspective from quite different sources. The procedures for executing his own painting—plotting lines of sight on a plane surface—he could have learned from the surveying techniques he employed while measuring the ruins of Rome. Perspective drawing is, after all, similar to surveying in that both involve determining the relative positions of three-dimensional objects for the purpose of protracting them on paper or canvas. The practice of measuring and surveying was highly developed by Filippo's time: his great leap appears to have been an application of its principles and techniques to the art of painting.
Filippo's experiment consisted of an almost magical optical trick, a trompe l'oeil painting that, in its clever confusion of life and art, prefigured much later experiments with optical devices such as cameras obscura, panoramas, dioramas, and catoptric art. This painting—one of the most famous in the history of art—has long since been lost to the world. Last know to have been in the possession of Lorenzo the Magnificent, it vanished after the occupation of Florence by Charles VIII of France in 1494, when many works of Florentine art were looted. It was clearly described, however, by Antonio Manetti, who claimed to have held it in his hands and attempted the experiment himself.
For the subject of his perspective painting Filippo chose one of Florence's most familiar sights: the Baptistery of San Giovanni. Positioning himself a short distance inside the middle portal of Santa Maria del Fiore, some 115 feet from the Baptistery, he painted onto a small panel, in perfect perspective, using a geometrically constructed picture plane, everything that was visible through the "frame" of the cathedral's doorway: the Baptistery and its surrounding streets . . . In place of a painted sky he substituted a piece of burnished silver, a mirror that would reflect the clouds, birds, and changing sunlight of the actual sky. Finally, he drilled a small hole the size of a lentil bean into the vanishing point of the painting, or that central point on the horizon when the receding parallel lines appear to converge.
The panel was then ready for demonstration. Standing six feet inside the doorway of Santa Maria del Fiore—on the exact spot, in other words, where Filippo had executed the panel—the observer was to turn the painted side of the panel away from himself and peer through the small aperture. In his other hand he was to hold a mirror, the reflection of which, when the glass was held at arm's length, showed (in reverse) the painted image of the Baptistery and the Piazza San Giovanni. So lifelike was this reflection that the observer was unable to tell whether the peephole revealed the actual scene that should have been before him—the "real scene" lying beyond the panel—or only a perfect illusion of that reality. [33-36]