This review article of Frederik Stjernfelt’s Sheets, Diagrams, and Realism (2022) argues that Peirce’s theory of iconicity with its subdivision into the image-diagram-metaphor triad must not be reduced to diagrammatic iconicity. The foundation of the triadic subdivision of the icon is not in Peirce’s diagrammatic logic but in Peirce’s cenopythagorean categories. A focus is on misinterpretations of Peirce’s concept of thirdness in the firstness of the icon. The paper argues that not only metaphors, but also comparisons, analogies, analogic arguments, and (...) examples belong to the third class of icons. (shrink)