Andrés de Olmos, Arte de la lengua mexicana (1547)

The grammar of Nahuatl that a Franciscan finished in 1547 at the convent of Hueytlalpan, twenty-five years before the oldest Nahuatl grammar that reached print. It stayed in manuscript for 328 years — no press, a dead printer, a dead patron — and was published at last in Paris in 1875 from two surviving copies. Its author says on the first page why he wrote it: charity, his prelate's order, and the salvation of the souls of "estos naturales indios".