Through the Veil (Crosby continued)

We all know the story of the Renaissance painters’ transition from flat Medieval iconography to more naturalistic, perspectival representations. The new style relied on a trompe l’oeil effect to project the impression of a third dimension back into the painting, as though the observer were looking through a window at the scene behind it. To achieve an accurate perspectival effect, artists had to capture the moment and the empty space.

We think of realistic art as the visualization of a scene at a single instant in time — kind of like a painted snapshot. Medievalists tended to paint whole stories: a single painting might, for example, depict Paul’s ship going aground, Paul struggling to shore, and Paul preaching to the pagans. Even the single moment is depicted “on the move”: the artist might show three sides of a rectangular building, which can’t be seen by standing in one place. We’re also used to seeing objects depicted in context, which means leaving spaces between things. Medieval artists didn’t do that: they crowded all the objects together — a style known as horror vacui, or fear of empty spaces (thanks to Jason Hesiak for that bit of art knowledge). It’s hard to represent either breadth or depth accurately without making room for the vacancies that spread the world apart.

Painting started moving toward modern realism in mid-13th century Italy. But even Giotto, the first acclaimed master of the new techniques, didn’t achieve perspectival accuracy. Ptolemy’s ancient method of representing surfaces via geometric gridwork, brought to Florence in 1400, had as much impact on painting as on cartography. A perspectival painting is like a geometrically accurate map of the scene depicted by the artist. The Florentine Alberti formalized perpsectival painting technique based on ancient Greek optical theory:

Seeing was a matter of information being acquired by the eye through a cone (or, as it was often called, a pyramid) of light extending out from the eye. An accurate picture was a slice of that cone, vertical to its central axis, made at whatever distance from the eye the picture taker selected.

To implement Ptolemy’s geometric techniques, Alberti recommended that the painter set up a veil between himself and the subject. The veil, a gridwork of fabric, was the slice through the visual cone.

One was to paint or draw not what one knew to be true about the scene — for instance, with parallel lines always the same distance apart — but strictly what one saw. What one saw was parallel lines angling toward each other the farther they extended away from the observer. One could measure how much they converged in appearance by gazing at them through the veil and counting threads. Then one would transfer that to a flat surface on which one had carefully drawn lines equivalent to the veil’s threads. The veil enabled the painter to quantify not reality, but something more subtle: the perception of reality.

Medieval Italian streets and floors really are constructed from a gridwork of stones or tiles, but the reason they appear in all those masterpieces by Leonardo and Raphael and Michelangelo is to establish the costruzione legitima, the perspectival geometry on which Renaissance painting was based.

The intellectuals of the Middle Ages respected mathematics in the abstract and tended to veer away from it in practice. Those of the Renaissance respected mathematics, especially geometry, and utilized it extravagantly in practice… The artists of the Renaissance avant-garde, who were often architects, engineers, artisans, and mathematicians as well as painters, were obsessed with space-as-geometry.