MELODY. - It is the essence of music, its vital substance organized into discourse and unfolding a musical thought within II.
Since a horizontal alignment of sounds cannot fail to suggest harmonies, even if these remain implied, every melody carries the sonic relations inherent in its own complex of sounds (in its field). And since each of the sounds forming the melody in the dual order of succession and simultaneity has its own duration (precise or imprecise), melody is also necessarily rhythm. Yet no succession and simultaneity of sounds exists in reality independently of a vibrating body that produces the sounds themselves: melody therefore also involves timbre. It unifies all the elements of musical discourse.
It is universally admitted that the essence of music is vocal: consequently, the vocal character is fundamental even in melody (it should be remembered, however, that "vocal" does not coincide with "cantabile" in the current sense of easy and evident linear symmetry).
The principal forms of melody are as follows.
1) Strophic form. - The strophic forms of poetry set to music determine (though not always) analogous strophic structures in the associated music. Such musical strophic form attains its most elementary symmetrical order in the "square" melody, in which the first two phrases, each of two measures, form the first half-phrase, which, attaching itself to the following phrase of equal breadth, forms the phrase of eight measures: two phrases constitute the square period (sixteen measures). Contractions or expansions of phrases or phrases may produce an irregular square. The square type is found in song forms, in the Lied, in hymns, and, independently of a poetic text, in dance forms (strophic instrumental melody). But strophic form does not always mean squareness, just as a stanza does not always mean verse. Even an unmetrical text can have strophic form, and likewise musical discourse is strophic if it proceeds by closed periods but not therefore of sixteen measures.
2) Multiple (or thematic) melody. - In polyphony, the discourse is woven of themes that interlock, reproduce themselves, modify themselves, generate others, pass from one voice to another, permeating all the parts with their influence.
3) Infinite melody. - Free from cadential symmetries and from conclusions of a strophic nature, it does not for that reason proceed without its own logic, but this latter reduces to a pure necessity of effusion in continuous renewal. The most luminous examples are given by melismatic chant in the liturgy (Gregorian graduals and alleluias; Ambrosian psalms and alleluias).
BIBL.:
Carducci Edgardo, *La melodia infinita*, Roma 1938.