Created by Giuliano da Maiano in the 15th century, the walls of the studiolo from the ducal palace in Gubbio, Italy, feature elaborate trompe-l’œil illusions. The wall shown above is flat — the images of the bench, the open cabinets, their contents, and even the shadows are all meticulously fashioned from inlaid walnut (see below).

The perspective is carefully arranged, with a consistent horizon line and vanishing points. The illusion works best for a viewer 1.68 meters tall standing at a prescribed point along the entrance of the window niche. “When the studiolo’s doors were closed and the main window was covered by a pair of now-lost shutters, the viewer would have been surrounded by an illusionary but convincing space based on four converging perspectives.”

(From Olga Raggio, Federic da Montefeltro’s Palace at Gubbio and Its Studiolo, 1999.)

In 1808, English artist Benjamin Haydon was midway through painting the assassination of Dentatus when a friend convinced him to visit the Elgin Marbles, sculptures from the Parthenon recently brought to Britain:

The first thing I fixed my eyes on was the wrist of a figure in one of the female groups, in which were visible, though in a feminine form, the radius and ulna. I was astonished, for I had never seen them hinted at in any female wrist in the antique. I darted my eye to the elbow, and saw the outer condyle visibly affecting the shape as in nature. I saw that the arm was in repose and the soft parts in relaxation. That combination of nature and idea which I had felt was so much wanting for high art was here displayed to mid-day conviction. My heart beat! If I had seen nothing else I had beheld sufficient to keep me to nature for the rest of my life. But when I turned to the Theseus and saw that every form was altered by action or repose, — when I saw that the two sides of his back varied, one side stretched from the shoulder-blade being pulled forward, and the other side compressed from the shoulder-blade being pushed close to the spine as he rested on his elbow, with the belly flat because the bowels fell into the pelvis as he sat, — and when, turning to the Ilissus, I saw the belly protruded, from the figure lying on its side, — and again, when in the figure of the fighting metope I saw the muscle shown under the one arm-pit in that instantaneous action of darting out, and left out in the other arm-pits because not wanted — when I saw, in fact, the most heroic style of art combined with all the essential detail of actual life, the thing was done at once and for ever.

He “dashed out the abominable mass” of his own painting and devoted himself thereafter to drawing the marbles for as many as 15 hours a day. When he took the Swiss painter Henry Fuseli to see them, “Never shall I forget his uncompromising enthusiasm. He strode about saying, ‘De Greeks were godes! de Greeks were godes!'”

In a 1946 essay, Warner Brothers animator Chuck Jones presented two shapes:

These represent two nonsense words, tackety and goloomb. Which is which? Most people decide immediately that the shape on the left is tackety — even though that word has no meaning.

Similarly, one of these shapes is a bassoon, and one is a harp:

Here again, the correspondence seems obvious. “These are static examples of what are mostly static sounds,” Jones wrote. “The art of animation brings them to life, brings them fluidity and power; endows them, in short, with the qualities of music. The field of graphic symbols is a great but highly unexplored field. It will, I believe, prove an important one to the musician, and to any audience that is interested in satisfying the visual appetite, side by side with the auditory appetite.”

German-American psychologist Wolfgang Köhler had considered the same question in 1929. It’s been documented as “the bouba/kiki effect.”

(Chuck Jones, “Music and the Animated Cartoon,” Hollywood Quarterly 1:4 [1946], 364-370.)

A woman told James McNeill Whistler that the view of the Thames she had just seen reminded her exactly of his series of paintings.

He told her, “Yes, madam. Nature is creeping up.”