Glosas
Instrumental variations on well-known melodies in Spanish lute and organ music of the 16th century.
What it means
Glosas, Spanish for “glosses” or “commentaries,” are instrumental variations on a well-known melody or bass, as cultivated in Spanish lute, vihuela, and organ music of the 16th century. The model, often a song or dance, is not altered but “commented on” with runs, turns, and small figures.
Musical use
The glosas belong to the diminution practice of the Renaissance: long notes are dissolved into quick figures and leave the melody recognisable in the background. An important source is Diego Ortiz's Tratado de glosas, printed in Rome in 1553, which gives rules and examples for embellishing vocal settings and basses. Similar procedures are found in the “diferencias” of Spanish composers such as Antonio de Cabezón.
Glosas should be distinguished from the free fantasia, which needs no known model, and from the Baroque variation, which often changes the harmony. Glosas stay close to their model and live on embellishment.
Performance practice
When playing glosas, keep the underlying melody or bass in your ear and shape the figures so that they play around the model but do not cover it. Choose a tempo in which the quick runs sound clear and even.