A student in both schools was the Portuguese GREGORIO SILVESTRE (1520-70), choirmaster and organist in the Cathedral of Granada, who, beginning with a boy's admiration for Garci Sánchez and Torres Naharro, practised the _redondilla_ with such success as to be esteemed an expert in the art. A certain Pedro de Cáceres y Espinosa, in a _Discurso_ prefixed to Silvestre's poems (1582), tells us that his author "imitated Cristóbal de Castillejo, in speaking ill of the Italian arrangements," and that he cultivated the novelties for the practical reason that they were popular. It is certain that Silvestre is as attractive in the new as in the old kind, that his elegance never obscures his simplicity, that he shows a rare sense of ordered outline, an exceptional finish in the technical details of both manners. His conversion is the last that need be recorded here. The _villancico_ still found its supporters among men of letters, and, as late as the seventeenth century, both Cervantes and Lope de Vega profess a platonic attachment to it and kindred metres; but the public mind was set against a revival, and Cervantes and Lope were forced to abandon any idea (if, indeed, they ever entertained it) of breathing life into these dead bones. Didactic prose was practised, according to the old tradition, by Juan López de Vivero Palacios Rubios, who published in 1524 his _Tratado del esfuerzo bélico heróico_, a pseudo-philosophic inquiry into the origin and nature of martial valour, written in a clear and forcible style. Francisco López de Villalobos (1473-1549), a Jewish convert attached to the royal household as physician, began by translating Pliny's _Amphitruo_ in such fashion as to bring down on him the thunders of Hernán Núñez. Villalobos works the didactic vein in his rhymed _Sumario de Medicina_ which Ticknor ignores, though he mentions its late derivatives, the _Trescientas preguntas_ of Alonso López de Corelas (1546) and the _Cuatrocientas respuestas_ of Luis de Escobar (1552). But the witty physician's most praiseworthy performance is his _Tratado de las tres Grandes_—namely, talkativeness, obstinacy, and laughter—where his familiar humour, his frolic, fantasy, and perverse acuteness far outshine the sham philosophy and the magisterial intention of his other work. A graver talent is that of Fernando Pérez de Oliva (1492-1530), once lecturer in the University of Paris, and, later, Rector of Salamanca, who boasts of having travelled three thousand leagues in pursuit of culture. His _Diálogo de la Dignidad del Hombre_, written to show that Castilian is as good a vehicle as the more fashionable Latin for the discussion of transcendental matters, is an excellent example of cold, stately, Ciceronian prose, and the continuation by his friend, Francisco Cervantes de Salazar, is worthy of the beginning; but the hold of ecclesiastical Latin was too fast to be loosed at a first attempt.