After 15 years in the service of the Duke of Ferrara, he resigned and withdrew to his family estate, the Villa Guarina, where he wrote his most notable work, Il pastor fido (1590; The Faithful Shepherd, 1647). This play, a pastoral tragicomedy, polished in style, was translated into many languages and became popular during the 17th century. It set the pattern for a code of refinement and gallantry that lasted until the late 18th century.
Guarini's work, however, lacks the deep feeling and sentiment of his predecessor at the court of d'Este, Torquato Tasso.