"Celestina", and Celestina herself is developed from the Trotaconventos of Ruiz. Moreover, Ruiz was justly proud of his metrical innovations: the "Libro de buen amor" is mainly written in the "cuaderna via" modelled on the French alexandrine, but he imparts to the measure a variety and rapidity previously unknown in Castilian, and he experiments by introducing internal rhymes or by shortening the fourth line into an octosyllabic verse; or he boldly recasts the form of the stanza, extending it to six or seven lines with alternate verses of eight and five syllables. But his technical skill never sinks to triviality. All his writing bears the stamp of a unique personality, and, if he never attempts a sublime flight, he conveys with contagious force his enthusiasm for life under any conditions — in town, country, vagabondage