“Perhaps the most obvious thing called into question by this meta-picture is the structure of ‘inside and outside,’ first- and second-order representation, on which the whole concept of ‘meta-‘ is based. And image of nested, concentric spaces and levels is required to stabilize a metapicture, or any second-order discourse, to separate it cleanly from the first-order object-language it describes. Thus, most metapictures depict a picture-within-a-picture that is simply one among the many objects represented. Even a picture-within-a-picture that duplicates its framing image (the effect of the mise en abime) can, in principle, keep its levels, boundaries, and frames distinct. […] It is a metapicture in a strict formal sense, a picture about itself, a picture that refers to its own making, yet one that dissolves the boundary between inside and outside, first- and second-order representation, on which the metapictorial structure depends”

— WJT Mitchell, Picture Theory

[update: see also]