The article starts from the mystical and mathematical axiom of “squaring the circle”, exploring both geometric and sacred forms—the square and the sphere—and the epistemological vocabulary deriving from and permitted by them, appropriated by two distinct semiotic theories. More than theoretical or cognitive solutions, the form and vocabulary adopted by a theory are fundamental pieces in reconstructing what world visions are enabled in its application: a semiotic theory in the image of the square and planes facilitates an understanding of reality radically diverse to a semiotic of spheres. I will aim to explore and analyse this distinction of the theoretical vision imprinted in the image and vocabulary utilised by those theories, reflecting on the traces of cosmologies, mystical, hermetic, and religious principles they carry. Rather than a guise of comparison, I intend to contrast the theories in search of a third sacred form that manifests the squared circle: the firmament. Exploring particularly Greimas’ work De L’imperfection and Lotman’s image of the explosion, the work aims to argue for holistic approaches in semiotic studies, searching for spaces of overlap where Greimas and Lotman approximate the image of the firmament from Abrahamic cosmology: a domed plane reuniting both square and sphere. Beyond the goal of falsifying competing theories, this proposition aims to reflect on the union of forms, striving to weave in connections that permit analyses contemplating both the planar and spherical aspects of our discourses and other meaning-making manifestations.