What is the form of Josquin des Prez's "Ave Maria . . . virgo serena"?

The form of Josquin des Prez's "Ave Maria . . . virgo serena" is indeed a strophic prayer to the Virgin Mary. This piece is structured in a way that emphasizes repetition and variation in the musical setting of the text. The strophic form typically involves using the same music for each stanza of text, which aligns with the liturgical tradition of setting prayers and hymns to music. In this case, the piece is designed to honor the Virgin Mary, reflecting the reverence found in sacred choral music of the Renaissance period. The text's devotional nature and the music's melodic and harmonic simplicity contribute to its effectiveness as a prayer.

While sonata form, through-composed style, and Baroque opera represent other musical formats and styles, they do not apply to this specific work. Sonata form is characterized by its development and recapitulation sections, while through-composed refers to a composition that does not repeat sections or verses. Baroque opera, on the other hand, emerged later and is associated with dramatic narratives and stage performances, which is not the context for Josquin's choral piece. Thus, the identification of the work as a strophic prayer highlights its appropriate context within Renaissance sacred music.