Petrarch's Liber sine nomine is a collection of nineteen letters on the corruption of the papal court at Avignon, and on Petrarch's hopes for the reestablishment of the temporal spiritual preeminence of Rome. These letters represent the impassioned criticism of an intelligent observer who had first-hand knowledge of the corruption of Avignon, "the newest Babylon." Avignon is "where frankness is called foolishness, cunning is called wisdom, God is despised, money worshipped, the laws trodden underfoot." Rome, where Petrarch believed the papacy rightfully should be located, was "the holy mother, the queen of cities." Indeed, his indictment of the papacy was so unremitting, that Petrarch had to exclude the letters from his collected Epistolae familiares, hold them back from publication until after his death, and remove the names of his correspondents as well as most clues to their identities.
Famous Italian poet, scholar, and humanist Francesco Petrarca, known in English as Petrarch, collected love lyrics in Canzoniere.
People often call Petrarch the earliest Renaissance "father of humanism". Based on Petrarch's works, and to a lesser extent those of Dante Alighieri and Giovanni Boccaccio, Pietro Bembo in the 16th century created the model for the modern Italian language, which the Accademia della Crusca later endorsed. People credit Petrarch with developing the sonnet. They admired and imitated his sonnets, a model for lyrical poems throughout Europe during the Renaissance. Petrarch called the Middle Ages the Dark Ages.