Peirce’s architectonics, far from rigid, is bended by many plastic transformations, deriving from the cenopythagorean categories, the pragmaticist (modal) maxim, the logic of abduction, the synechistic hypotheses and the triadic classification of sciences, among many other tools capable of molding knowledge. Plasticity, in turn, points to interlacements between mathematics and art, and shapes some associated conceptual forces in the boundary of the disciplines: variation, modulation and invariance; transformability, continuity and discreteness; creative emergence. In this article we focus on this third aspect, through bounded, well defined case studies in the Logic Notebook. The first section describes the manuscript and its interest for a study of creativity, leading to a short speculation on “creative reason” and “plastic imagination” in Peirce. The second section studies five precise cases of creative emergence in the Logic Notebook: differential relatives, existential graphs, sequence diagrams, triadic logic, translatability. Some major surprises occur in those detailed studies.