trompe l'œil

The oldest case, and the reason nothing in the argument depends on the machinery being new. An image that works only from one position, whose success is measured not by any property of the surface but by a failure of discrimination in the person looking. The boundary it defeats is figure/ground, and it defeats it in a beholder, several centuries before there was a vocabulary for saying so — which is the strongest available evidence that the space between describes something structural rather than a recent theoretical preference.