The unification of the theory of semiotics has been an ambition of the IASS-AIS since the First World Congress in 1974. In his Preface to the Proceedings, Umberto Eco set the participants with certain fundamental tasks, including “providing the discipline with a unified methodology and a unified objective.” At the Second Congress, however, the multitude of topics and approaches led to the prevailing question of the Closing Session: “Can Semiotics Be Unified?” By the Fifth Congress the organizers would claim that theoretical differences “served to strengthen rather than to divide.” This paper traces the origin of this disunity to the writings of Aristotle and their interpretation by late classical and medieval theologians. Received wisdom tells us that linguistic semiology forms a part of general semiotics – the part dealing with either linguistic or conventional signs. This paper overturns that view, demonstrating that (linguistic) relations of equivalence and (semiotic) relations of implication operate in perpendicular planes of semiosis, intersecting at the point of the thing itself. These two planes of semiosis exist as unconnected theories in Aristotle, but become conflated in Augustine. This paper resolves the relationship between semiotics and semiology and in doing so, provides a unified methodology and objective.