The Madrigal is defined as a secular (not of the church) work for singers, originating in Renaissance Italy and set to short lyrical poems. Madrigals were very popular in the 1500s and represented some of the first popularly published and sold music. Folks could spread a madrigal out on the table and try their hands, or voices, at it, delighting in the intricate vocal weavings and appealing, often naughty lyrics. The words to this more restrained madrigal of Palestrina go thusly:
On the bank of the Tiber, a youth I see,
A charming shepherd, a charming youthful shepherd,
Voicing his feeling there:
Be satisfied, O cruel Goddess, with my woe and pain.
But a dead man cannot say that sorrow kills him.
Alas, wretched fate!
Skillful composers have a bag of tricks to pull from in setting such words to music. Generally, the idea is to understand the words and match those words with musical gestures of similar meaning. What meaning do you extract from the poetry above and what do you hear in Palestrina's setting that expresses it?
Madrigals are often built on melodic figures and phrases, fragmented and repeated and spilling over one another in delightful counterpart. Palestrina crafted a downward-moving melodic figure in this piece to match the somberness of the poetry. The sinking feeling you get listening to "Alla Riva del Tebro" is the result of these crest-fallen melodies, tumbling one over the other.
Palestrina loved the rigorous discipline and craftsmanlike order that we hear in "Alla Riva del Tebro." But he may have been prevented by the politics of the day from indulging in more madrigal writing, walking a fine line between the worldly madrigals adored by the public and the purer, sacred music demanded by the church.