Pereira studied humanities and theology, and finally law at the University of Santiago de Compostela in Spain, graduating in 1845.
In 1840 he founded an academy of arts and literature in Santiago, bringing together the best in the region.
Posada founded La Aurora de Galicia, a magazine of literature, science, and art, in 1845.
While in Vigo, using the pen name Don Lucas, Posada regularly published humorous writings as well as poetry in the Galician language and legends or leyenda.
His legends or leyenda, inspired by the traditional romances, are highlighted by Rosalida (which was influenced by the Romance del Conde Olinos, a children's song) and La Bella Infanta (The Beautiful Infant).