The performance begins with a prologue by Mercury which is nothing but a short argument of the whole plot.  ‘Mercurio annunzia la festa’ is the superscription in the original, evidently suggested by the appearance of ‘un messo di Dio’ with which the religious rappresentazioni usually open.  At the end of this prologue a shepherd appears and finishes the second octave with the couplet: 

    State attenti, brigata; buono augurio;
    Poi che di cielo in terra vien Mercurio.

In the Ferrarese revision these stanzas appear as ‘Argomento’ without mention of Mercury, while for the above lines are substituted the astonishing doggerel: 

    Or stia ciascuno a tutti gli atti intento,
    Che cinque sono; e questo e l’ argomento.

Thereupon (beginning Act I of the revision) enters Mopso, an old shepherd, meeting Aristeo, a youthful one, with his herdsman Tirsi.  Mopso asks whether his white calf has been seen, and Aristeo, who fancies he has heard a lowing from beyond the hill, sends his boy to see.  In the meanwhile he detains Mopso with an account of his love for a nymph he met the day before, and sings a canzona: 

    Ch’ i’ so che la mia ninfa il canto agogna[156].

It runs on the familiar themes of love:  ‘Di doman non c’ e certezza.’

    Digli, zampogna mia, come via fugge
      Con gli anni insieme la bellezza snella;
      E digli come il tempo ne distrugge,
      Ne l’ eta persa mai si rinovella;
      Digli che sappi usar sua forma bella,
      Che sempre mai non son rose e viole... 
    Udite, selve, mie dolci parole,
      Poi che la ninfa mia udir non vole.

The boy Tirsi now returns, having with much trouble driven the strayed calf back to the herd, and narrates how he saw an unknown nymph of wondrous beauty gathering flowers about the hill.  Aristeo recognizes from this description the object of his love, and, leaving Mopso and Tirsi to shake their heads over his midsummer madness, goes off to find her.

So far we might be reading one of the ecloghe rappresentative which we shall have to consider shortly, but of which the earliest known examples cannot well be less than ten or twelve years later than Poliziano’s play.  With the exception, indeed, of one or two in Boccaccio’s Ameto, it is doubtful whether any vernacular eclogues had appeared at the time.  The character of Tirsi belongs to rustic tradition, and must be an experiment contemporary with, if not prior to, Lorenzo’s Nencia.  The portion before the canzone is in terza rima; that after it, like the prologue, in octaves.

The original proceeds without break to the song of Aristeo as he pursues the flying Euridice (Act II in the revision): 

    Poi che ’l pregar non vale,
      E tu via ti dilegui,
      El convien ch’ io ti segui. 
    Porgimi, Amor, porgimi or le tue ale.