Italian literature is written in the Italian language, particularly within Italy. It may also refer to literature written by Italians or in Italy in other languages spoken in Italy, often languages that are closely related to modern Italian. An early example of Italian literature is the tradition of vernacular lyric poetry performed in Occitan, which reached Italy by the end of the 12th century. In 1230, the Sicilian School is notable for being the first style in standard Italian. Dante, one of the greatest of Italian poets, is notable for his Divina Commedia. Petrarch did classical research and wrote lyric poetry. Renaissance humanism developed during the 14th and the beginning of the 15th centuries. Humanists sought to create a citizenry able to speak and write with eloquence and clarity. Early humanists, such as Petrarch, were great collectors of antique manuscripts. Lorenzo de Medici shows the influence of Florence on the Renaissance. Leonardo da Vinci wrote a treatise on painting. The development of the drama in the 15th century was very great. The fundamental characteristic of the era following Renaissance is that it perfected the Italian character of its language. Machiavelli and Guicciardini were the chief originators of the science of history. Pietro Bembo was an influential figure in the development of the Italian language and an influence on the 16th-century revival of interest in the works of Petrarch.