Linear perspective—how to render depth in a picture or relief according to strict geometrical laws—was discovered in the early years of the Renaissance and it fascinated artists for two or three generations, as well it might. It was one of the biggest breakthrough discoveries painting ever saw. An artist could now include in the frame of his picture not only what was happening “up front” but what was going on “behind” the front-line figure, including the landscape and the sky all the way to the horizon. He could paint a view of anything just the way the eye really sees it.
Men like Uccello got so excited over this new discovery that they began to lose themselves in study and speculation. Some believed that where that new law came from there might be more and they wracked their brains day and night to find them. Uccello made pictures to astound the viewer—broad, very three dimensional, battle scenes, with daring foreshortening and deep landscape. The better to trick the eye, he accentuated the new perspective lines, laying jousting lances along them or other battle detritus or even a fallen soldier. In some paintings the scenes took place on a black-and-white tile floor, like a chessboard, which was a very graphic way to show things tapering off to the horizon. Of course, many of these early experiments are flops: the painter tries too hard to trick the eye and the eye isn’t that dumb: it sees the artifice. It also sees right off when the foreshortening is faulty. Look at the fallen knight in this Uccello:
Paolo Niccolò da Tolentino Leads the Florentine Troops (tempera on wood, 182 x 320 cm.) National Gallery, London