senior poet of the Sicilian school and notary at the court of the Holy Roman emperor Frederick II. Celebrated during his life, he was acclaimed as a master by the poets of the following generation, including Dante, who memorialized him in the Purgatorio (XXIV, 55–57).

Giacomo is traditionally credited with the invention of the sonnet, and his works in that form remain the earliest known. He adapted the themes, style, and language of Provençal poetry to Italian, infusing it with his own aristocratic and exclusive tastes. All his extant poetry—some 40 lyrics, including sonnets, canzoni, tenzoni (poetic debates), and one discordo (poetic disagreement)—concerns the theme of love, which, in the courtly tradition, is seen in feudal terms as the service of the lover to his lady. None of his poetry survives in the original Sicilian dialect but has, rather, been modified to conform to Tuscan.