In many instances, it seems to be psychologically necessary to mark out the boundariesbetween the world of everyday experience and a world which has special semanticsignificance. Thus in the theater the frame is expressed through such stage devicesas footlights, curtains, and so forth. ... Sometimes the borders of the conventionalartistic space may fluctuate, without, however, being entirely destroyed, as in the caseof carnival or mystery plays where theatrical conventions expand into life [81, p138].