The most pretentious treatise on Castilian versification before the Golden Age is the “Libro segundo en que trata de la prosodia i sîlaba” of Antonio de Nebrija's Gramdtica castellana, first published in 1492. It is written by a scholar—not a poet, though Nebrija, Spain's first great humanist, did write some verses—a scholar whose classic learning determined his approach to the study of the vernacular in matters of versification. Nebrija's learning, however, did not blind him to the fundamental facts of Castilian practice in verse, though it may have slightly obscured his vision at times and warped his interpretation of certain phases of Spanish metrics. And it did cause him to discover in Castilian verse certain fundamental principles hidden from many theorists and prosodists even to the present day, yet for centuries instinctively practiced by poets. Nebrija studied and analyzed the nature of Castilian verse “en el buen uso” (Cap. viii) as it existed shortly before the introduction of Italianate meters in Spanish. The time is significant, as En-cina explains in the introduction to his Arte de poesia castellana (p. ii):