Organum

ORGANUM (equivalent to Diaphonia; and, though less exactly, to Discantus). It is impossible to ascertain the date at which Plain Chaunt was first harmonised; and equally so, to discover the name of the Musician who first sang it in harmony. We know, however, that the primitive and miserably imperfect Counterpoint with which it was first accompanied was called Organum; and we have irrefragable proof that this Organum was known at least as early as 880; for Scotus Erigena, who died about...