The ''Micrologus'' is a treatise on
Medieval music
Medieval music encompasses the sacred and secular music of Western Europe during the Middle Ages, from approximately the 6th to 15th centuries. It is the first and longest major era of Western classical music and followed by the Renaissance ...
written by
Guido of Arezzo, dating to approximately 1026. It was dedicated to
Tedald, Bishop of Arezzo. This treatise outlines singing and teaching practice for
Gregorian chant, and has considerable discussion of the composition of polyphonic music.
This treatise discusses modified parallel
organum as well as free organum. The examples given are in two voices, set note-against-note, and the voices are frequently permitted to
cross
A cross is a geometrical figure consisting of two intersecting lines or bars, usually perpendicular to each other. The lines usually run vertically and horizontally. A cross of oblique lines, in the shape of the Latin letter X, is termed a s ...
. He advised against use of the
perfect fifth
In music theory, a perfect fifth is the Interval (music), musical interval corresponding to a pair of pitch (music), pitches with a frequency ratio of 3:2, or very nearly so.
In classical music from Western culture, a fifth is the interval fro ...
and
minor second, favouring instead the
major second and
perfect fourth (though thirds were also permitted).
One point of importance is his guideline for the occursus (meaning "meeting" or "concurrence", running on the same path), which is a predecessor of the later
cadence
In Western musical theory, a cadence (Latin ''cadentia'', "a falling") is the end of a phrase in which the melody or harmony creates a sense of full or partial resolution, especially in music of the 16th century onwards. Don Michael Randel ( ...
. An occursus occurs where two voices approach a
unison. He suggested that the unison should be approached either by
contrary motion
In music theory, contrapuntal motion is the general movement of two melodic lines with respect to each other. In traditional four-part harmony, it is important that lines maintain their independence, an effect which can be achieved by the judic ...
from a
major third, or
oblique motion from a
major second.
[Hoppin, Richard H. ''Medieval Music''. Norton, 1978, pp. 194-195.]
References
External links
Micrologus Guidonis de disciplina artis musicae
Medieval music manuscript sources
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