The scholars of the 11th- and 12th-century legal schools in Italy, France and Germany are identified as glossators in a specific sense. They studied Roman law based on the Digesta, the Codex of Justinian, the Authenticum (an abridged Latin translation of selected constitutions of Justinian, promulgated in Greek after the enactment of the Codex and therefore called Novellae), and his law manual, the Institutiones Iustiniani, compiled together in the Corpus Iuris Civilis. (This title is itself only a sixteenth-century printers' invention.) Their work transformed the inherited ancient texts into a living tradition of medieval Roman law.
The glossators conducted detailed text studies that resulted in collections of explanations. For their work they used a method of study unknown to the Romans themselves, insisting that contradictions in the legal material were only apparent. They tried to harmonize the sources in the conviction that for every legal question only one binding rule exists. Thus they approached these legal sources in a dialectical way, which is a characteristic of medieval scholasticism. They sometimes needed to invent new concepts not found in Roman law, such as half-proof (evidence short of full proof but of some force, such as a single witness). In other medieval disciplines, for example theology and philosophy, glosses were also made on the main authoritative texts.
