Valdelomar promised to provide a prologue for Vallejo's first collection of poetry, Los heraldos negros, but his ambitious lecture tours of the provinces distracted his attention. Vallejo's collection finally appeared without the prologue in 1919, although it had been completed in 1918—which has led to some confusion over its publication date. In the meantime, Valdelomar was giving lectures the length and breadth of the country; as part of his commitment to reaching and educating a broad audience, but also as part and parcel of his efficient showmanship and entrepreneurial sense, he offered this first lectures in each town at a discount price—or for free—to workers and peasants, and later hiked up the admission price to a by-now eager public.
Valdelomar agreed to write a prologue for Vallejo's first poetry collection, Los heraldos negros. However, his lecture tours across the provinces prevented him from completing it on time. The book was eventually published in 1919 without the prologue, despite being finished in 1918—leading to confusion about its release date. During this period, Valdelomar gave lectures throughout the country; partly as a way to educate and reach various audiences, but also due to his engaging presentation style and business acumen, he offered these lectures at reduced or no cost to workers and peasants, and later raised admission fees for an eager public.