The text syllables were applied to them in the same manner as they were to the original melody.
When, in the eleventh century, one or more added (or organal) voices were beginning to be sung in contrary motion to that of the original melody, they would begin on the initial note of the melody, on its octave or on the fifth above, and at the end of the organum , or piece of music, return to their starting point, thus forming a final point of repose, consonance, or harmony.
Thus the laws of counterpoint and a system of notation fixing the exact time-value of each note (mensuralism) came into existence.
The necessity felt in music as in the other arts during the thirteenth and fourteenth centuries for greater expansion and freer expression originated, developed, and perfected many new forms.
The first interval which was used simultaneously with the melodic note was the fourth below (See COUNTERPOINT).
By doubling this interval in its upper octave, the interval of the fifth above the melodic note was formed, thus suggesting three-part harmony, which was introduced into practice later on.
With the Venetian masters the harmonic effect had become the chief aim instead of being a result incidental to the melodic co-operation of the parts. It was only a reflex of a departing glory, the effect of a cause which had been removed.
In the meantime, Gregorian chant , now poorly performed at best, gradually fell into almost complete disuse.
The endeavour to throw off the supremacy of the liturgical melody with its diatonic character (which was then and is now the expression in music of the spirit of the Church par excellence), and to substitute for it a system better adapted to the expression of individual thought and feeling, began as early as the first part of the thirteenth century. In the numerous instrumental and secular vocal forms which were developed at this time and later (ricercar, canzone, tiento, toccata, præambulum, capriccio, chanson, strambotto, madrigal), original melodies were often substituted for a cantus flrmus taken from the Gregorian chant.
The harmonic element gradually gained ascendancy over the melodic in the whole field of production, and exercised an ever-growing influence over the general taste.