The confusion over vowels (i/e and o/u) and final consonants, missing letters for Spanish sounds and the prestige of Spanish culture and writing may have contributed to the demise of over time, as eventually fell out of use in much of the Philippines. Learning the Latin alphabet also helped Filipinos to make socioeconomic progress under Spanish rule, as they could rise to relatively prestigious positions such as clerks, scribes and secretaries. By 1745, wrote in his "Arte de la lengua tagala" that "The Indian who knows how to read [ is now rare, and rarer still is one who knows how to write []. They now all read and write in our Castilian letters alphabet." Between 1751 and 1754, Juan José Delgado wrote that "the men devoted themselves to the use of our [Latin writing".