De los Reyes' interest in folklore continued. He collected materials, wrote for periodicals, and issued an open letter calling on readers to collect, publish, and organize a folklore society, which did not materialize. De los Reyes wrote "Folk-Lore" not just as a book for legends and fables, but eventually as "a general archive at the service of all sciences", expanding his definition of "folklore" to include "popular knowledge relevant to all sciences", including sections on religion, customs, literature, and articles on Diego Silang, millenarian revolts, and local miracles of the Virgin Mary.