Contrapunctus
Contrapuntal writing, as in Bach’s “Art of Fugue.”
What it means
Contrapunctus is the Latin designation for counterpoint and derives from punctus contra punctum, “note against note” — originally in the sense of the note signs that are set in one voice against those of another. What is meant is the art of leading several independent voices so that they yield meaningful sonorities at the same time and yet each remains an independent line of its own.
Musical use
As a work designation the word appears above all in Bach's “Art of Fugue,” whose movements are counted as Contrapunctus. The choice is telling: the movements are fugues and fugue-related pieces of different construction — simple, counter-, double, triple, and mirror fugues — and the heading names what they have in common, namely the contrapuntal procedure, instead of the respective form.
As a teaching term, the Latin expression stands in the tradition of the study of composition, which has described the rules of voice-leading since the Middle Ages. An influential textbook of the early eighteenth century arranged the material in successive species, beginning with the note-against-note texture over a cantus firmus; this species counterpoint shapes teaching to this day.
Among the basic rules are the preference for contrary motion, the ban on parallel fifths and octaves, the regulated treatment of dissonance through preparation and resolution, and the singability of every individual voice. To these are added artful procedures such as double counterpoint, in which two voices can be exchanged, and the transformation of a theme through inversion, retrograde, augmentation, and diminution.
Other names
Counterpoint is the English designation for counterpoint as a discipline of composition. The Latin form contrapunctus is also used as the heading of individual pieces, best known in Bach's “Art of Fugue.” Both go back to punctus contra punctum, note against note.
Performance practice
Practise contrapuntal pieces voice by voice before you put them together, and sing each voice at least once. When playing, take care that no voice covers another; the lead changes, and the subject entry should be audible whatever register it stands in.