Ghiberti's "Commentario" includes the earliest known surviving autobiography of an artist. He discusses the development of art from the time of Cimabue through to his own work. In describing his second bronze portal for the Florence Baptistry, he states: "In this work I sought to imitate nature as closely as possible, both in proportions and in perspective... the buildings appear as seen by the eye of one who gazes on them from a distance." The language Ghiberti used to describe his art has proved invaluable to art historians in understanding the aims Renaissance artists were striving for in their artworks.