Apertus

What it means

Apertus — “open” — denotes in medieval music the first of two endings of a repeated section. Its counterpart is clausus, the “closed” second ending. On the first pass the section ends open and leads back to the repetition; on the second it ends closed on the final note.

Musical use

The procedure is widespread in secular song forms and dances of the fourteenth and fifteenth centuries, especially in the French forms whose sections are repeated. In the sources the section is notated only once, followed by the two different closing turns, marked accordingly — in French ouvert and clos.

In sound the open ending usually ends on a note that is not the final, frequently a whole tone above or below it, and thereby leads one to expect a continuation. The closed ending ends on the final and rounds off. The relationship is akin to the later pair of half cadence and full cadence, but rests on modal cadence formation rather than on functional harmony.

The principle has persisted across centuries. In today’s notation the writing with numbered brackets over the closing bars, prima volta and seconda volta, corresponds to it and expresses the same thing: the same section, a different ending.

Both endings share the preceding section, which is repeated, and differ only in the closing turn. The arrangement is found in the estampie and in secular song forms of the fourteenth century such as the ballade and virelai. It is a forerunner of the later repeat endings prima and seconda volta, which present the same principle in modern notation. Unlike there, the open ending often lies on a note other than the final.

Performance practice

Shape the open ending as a transition and not as an end — the music returns, and the sound should prepare that. Set the closed ending as an arrival. And with editions of early music read exactly which ending belongs to which pass; the designations often stand small above the notes.