In 1804, the Portuguese abbot, diplomat, and scholar José Correia da Serra was residing in Paris, having been obliged two years earlier to resign from his position at the Portuguese embassy in London owing to conflicts with the ambassador. Taking advantage of the opportunity to visit the Bibliothèque Nationale—formerly the French Royal Library, now owned by the nation in Napoleonic France—Correia da Serra came upon a four hundred-year old manuscript from his native land. It turned out to consist of two works by Duarte I of Portugal (r. 1433–1438), Leal Conselheiro (“the Faithful Counselor”) and the Livro do Cavalgar (“Book on Riding”). Duarte was known to Portuguese historians as a scholarly monarch, but until this time his reputation rested heavily on references in medieval Portuguese chronicles, since no copy of either of his two major works was known to have survived.

Correia da Serra never publicized his discovery; the manuscript was rediscovered about a decade later, and not until 1843 were its contents finally published. The texts have since been republished several times, but more than two centuries after their discovery, neither one has been made available in a viable English translation. The lack of attention to Duarte outside of Portugal reflects the underdeveloped state of Portuguese studies in the English-speaking world rather than the merits of his work: Duarte is among the most strikingly original authors of the Middle Ages, and had these works been composed by a Spanish or French monarch, they would assuredly be quite familiar to English-speaking scholars.