The volume focuses on the Latin tracts produced in Paris around 1270 by the Danes Martinus and Boethius de Dacia on what is known as "modistic grammar." The contours of this "medieval linguistics" become clear in the comparison with two further approaches to linguistic theory - four tracts by medieval Icelandic grammarians and Saussure's "Cours de linguistique générale" as a fundamental work in modern linguistics. The comparison then leads to a fundamental epistemological reflection on a possible typology of theoretical constructs in linguistics.