Sonsonate, authored the biography Vida y virtudes del venerable fray Andrés del Valle. Secular literature A major non-religious work was a manual for the manufacture of indigo El puntero apuntado con apuntes breves, by Juan de Dios del Cid, who made a rudimentary printing press to publish his work, which may have been the first press in the territory of El Salvador. The document is printed with the date 1641, but Salvadorean literary critic Luis Gallegos Valdés asserts that this date was a typographical error, and some historical references place it in the next century. Another major work was the Carta de Relación, written by the conquistador Pedro de Alvarado for practical reasons; it narrates major episodes in the conquest of the Americas. Literature during the era of independence By the last decades of Spanish rule there already existed considerable secular cultural activity in Central America. It was centered on the University of San Carlos in Guatemala. There, educated criollos gathered to discuss and exchange ideas of the Enlightenment. This encouraged the emergence of a literature more political than aesthetic, manifested principally in oratory and argumentative prose, both polemic and doctrinal, in which authors demonstrated their ingenuity and use of classical rhetoric. One major figure of this era was Father Manuel Aguilar (1750–1819), whose famous homily proclaimed the right of insurrection of oppressed peoples, provoking scandal and censorship. The priest José Simeón Cañas (1767–1838) is known for his 1823 speech in the Constituent Assembly, in which he demanded the emancipation of slaves. Presbyterian Isidro Menéndez (1795–1858), the author of much of the era's legislation, was also renowned for his oratory. The aesthetic of Salvadorean literature of this era did not have a role comparable to that of eloquent speech or journalistic writing. Literature was used only occasionally, such as anonymous verses offering satirical comment on contemporary politics, or other poetry celebrating the good name and deeds of important figures. Examples of the latter category include the prose work Tragedia de Morazán (Tragedy of Morazán) (1894) by Francisco Díaz (1812–1845) and the ode Al ciudadano José Cecilio del Valle (To the Citizen José Cecilio del Valle (1827) by Miguel Álvarez Castro (1795-1856). The weakness of the state, the lack of urban life, and the consequently non-existent cultural infrastructure limited authors' ability to support themselves. Under these conditions, artists were dependent on private patrons and oriented toward serving their tastes and increasing