According to legend, Giotto, while still an apprentice in Cimabue's workshop in thirteenth-century Florence, painted a fly on the nose of a portrait. The deception was so realistic that his master tried to brush it away. For Giotto, this witty trompe l'oeil was just a good-humored prank but today this kind of artistic deception is an earnest pursuit and big business.

Literally translated, trompe l'oeil means to 'deceive the eye'. For a split second, sometimes longer, the onlooker is fooled into believing that what he sees is real. Surprise is the vital element and the technique requires great skill and the consummate us of perspective. The first recorded example of this form of wallpainting is mentioned by the Roman author Pliny the Elder. More than two thousand years ago in Athens, the painter Zeuxis produced a painting of grapes so realistic that birds flew up to peck at them.

A trompe l'oeil panel is very personal and has a 'small is beautiful' intimacy about it. It feeds an almost universal desire to escape into a world where fantasy invades the senses. It needs very little space and, compared to a large wallpainting, is more affordable. Trompe l'oeil are also less intimidating and obtrusive to live with than a vast mural. On the other hand, by its nature, it tends to be a contrived rather than a passionate art form. The best trompe l'oeil murals go beyond visual deception and they unfold their secrets slowly as the inner eye adjusts from surprise to confusion. This is usually followed by a disappointing adjustment to reality-the grapes are not real after all-and, finally, delight at the skill of this visual confidence trick.

One of the modern masters of the art is the American Christian Thee. His world is a magical place both in the literal and the metaphorical sense. Thee is a prize-winning magician of the rabbit--out-of-a-hat variety, a stage designer, as well as a renowned exponent of trompe l'oeil. This ebullient and enthusiastic man imbues his audience with a sense of being caught up in his fantasies. He says that all his murals stem from his interest in designing for the theatre. Many of his smaller trompe l'oeil works are constructions-painted screens and shutters, window frames surrounding a mysterious figure or an intricate scene, painted on gessoed wood. Gesso is a fine plaster, bound with glue size, which builds up a hard surface on which the paint is then applied.

Thee has always had the ambition to incorporate magic in a painting. One of his most effective works is now owned by the Flint Institute of Art, Michigan (Plate 36). He calls it 'magic realism'. People looking at it revert to being children because they simply cannot figure out how it works. At first they see a pointed window covered by a pair of real shutters which are fixed to a wooden panel. When the shutters are pulled back, they reveal a predatory cat on a windowsill eyeing a caged canary. When the shutters are closed and reopened, the canary and cat have changed places. The castles in the sky have metamorphosed into clouds and the artist's name, or cartellino, which had been partly torn away, has been reinstated. The device is cleverly constructed with electronic magnets on the surface of one shutter and the canvas, but it would give the game away to reveal the complicated trickery involved and would spoil the illusion for future visitors to the Institute. This small trompe l'oeil is an ingenious combination of illusion, theatre, magic, and humor, and is typical of the artist, who says, 'I like to reward the onlooker who looks carefully by hiding small treasures in my murals'.