Andre Gide adopts the heraldic term mise en abyme, or a shield shown in the center of a shield, to describe a work within a work, like The Mousetrap in Hamlet, but Gide ultimately rejects such examples because The Mousetrap does not represent Hamlet as a whole, but only the actions of the characters within the play (as I discuss in Into the Abyss: The Mise en Abyme, the Art Work Within the Art Work). In turn Lucien Dällenbach challenges Gide’s metaphor of a shield within a shield, the heraldic device mise en abyme because the smaller shield does not represent the larger shield, but presents a new device. Dällenbach prefers the metaphor of a mirror, a metaphor Gide also use: “although Gide initially rejects the image of the mirror in favor of the one from heraldry, he later reverses this decision and enjoins us, if not purely and simply to substitute the idea of mirror reflection for that of the mise en abyme, at least to see the two terms as equivalent” (Dällenbach 34).
German Romantic writer Jean Paul defined philosophy in metaterms:
Whereas the entire Witz of philosophy is to make the subject “I” into an object and vice versa, the philosophy of the Witz nowadays is one that similarly tries to ensure that the ideas of this subject-object are treated sub-objectively; in other words, I am being profound and serious if I say, “I am registering the registering of the fact of registering the fact of registering’, or ‘I am reflecting on the fact of reflecting on the reflexion of a reflexion on a brush.’ These are serious sentences, which reveal infinite reflexion (‘Widerschein ins Unendliche’)! Such depths are certainly beyond the reach of some people! I’ll go further: only he who shows himself able to write, several times in a row, the genitive of the same infinitive of whatever verb, can be allowed to say: I am philosophizing . . .
Dallenbach, Lucien. The Mirror in the Text. Trans. Jeremy Whiteley and Emma Hughes. Chicago: The University of Chicago, 1989.