This portrait—among Bronzino's most arresting—was painted in the 1530s. [some sites say 1535-40] The sitter is not known, but he must have belonged to Bronzino's close circle of literary friends in Florence, a number of whom sat for the artist. Bronzino himself composed verses in the style of the great Florentine poet Petrarch (1304–74), and the fanciful and witty details in this picture—the carved grotesque heads on the table and chair and the masklike face suggested in the folds of the youth's breeches—would have been appreciated by writers as comments on masks and identity. The book is doubtless a collection of poems. For a technical study of the changes Bronzino made to the painting as he worked see metmuseum.org/collections. (http://www.metmuseum.org/art/collection/search/435802)