Garlandia

Christensen (2002), p. 628. In his treatise Johannes de Garlandia describes six species of mode, or six different ways in which longs and breves can be arranged.

However, this makes the first definitely identifiable scholar to accept and explain the mensural system to be de Muris, who can be said to have done for it what Garlandia did for the rhythmic modes.

Most of the surviving notated music of the 13th century uses the rhythmic modes as defined by Garlandia.