DISCANTUS. — With this term, which is considered a translation of the Greek διαφωνία, an ancient form of polyphony (v. ARS ANTIQUA) is indicated, succeeding the primitive organum or diaphony.
In addition to the contrary motion of the parts, a true mensuralism is established in this compositional genre (the diaphony was a simple note-against-note counterpoint, without measure or not measured in all its parts), whereby measured counterpoint is achieved, originally in two parts, then in three or four (Franco of Cologne), which move in contrary motion with equal texts (cantilenes, rondels, copulae, hoquets, etc.) or different texts (motets) at intervals of 5ths and octaves. True discantus differs from conductus, a sub-species of it, in that while in the latter all parts are freely invented by the same musician, it is composed over a given chant. Many anonymous theorists, the so-called "Catton," the two Francos of Cologne and Paris, Petrus de Cruce, I. de Garlandia, etc., provide rules for this form; their treatises on discantus are found in the Ambrosiana in Milan (ed. M. 17 dup. sec. xii), in the National Library in Paris (Fonds Sorbonne 1817, St-Victor 813 sec. xii), etc., while musical examples (13th century) are found in the aforementioned codex of the Ambrosiana, in one from Chartres (Bibl. de la Ville 130 [148]) and in one from Cambridge (Corpus Christi College 473, Winchester Troper).