As the physical impulse to seize things, itself than suspended and thus become metaphysical, the tactile hallucination is not that of objects but of death... every composition in trompe l'oeil contributes to the effect of loss, a sense of losing hold on the real through the very excess of its appearances. In trompe l'oeil objects are too much like the things they are: this close resemblance is like a second state, and their true relief, through this allegorical resemblance, through the diagonal light, is that of death.
Plato, who proposed the theory, seems to have done so in order to rule that the value of art is dubious. Since he considered ordinary material things as themselves mimetic objects, imitations of transcendent forms or structures, even the best painting of a bed would be only an "imitation of an imitation." For Plato, art is neither particularly useful (the painting of a bed is no good to sleep on), nor, in the strict sense, true. And Aristotle's arguments in defense of art do not really challenge Plato's view that all art is an elaborate trompe l'oeil, and therefore a lie. But he does dispute Plato's idea that art is useless. Lie or no, art has a certain value according to Aristotle because it is a form of therapy. Art is useful, after all, Aristotle counters, medicinally useful in that it arouses and purges dangerous emotions.