According to the original plan of the work, it would consist of three volumes. The first, published in the cited year, was about the impiety; the second, published three years later, referred to superstition, and the third, which was never published, would seek to fanaticism. Since the days in which appeared the work many are interrogated about who would be the recipient of the letters. Some thought that they were directed to light; but the fact that he wrote assiduously with this and that Luz made extensive commentary of the work, belies this idea. The most acceptable thesis is that is a character created by the imagination of Varela, as a symbol that reflected the Cuban youth.
Etymologically, Elpidio means hope and, at the beginning of the work, Varela writes, referring to youth: tell them that they are the sweet hope of the fatherland. For three years, Varela was holding strong polemics with the American Protestant theologians. In these polemics were evident differences between the Protestant and Catholic morality. In parallel, he received letters from Havana expressing the difficult situation prevailing in the island. This interaction arose the idea of letters to Elpidio. He wrote letters to Eusebius, against obstacles more economic that opposed a change in morality: IMPIETY and superstition, although I wish to write one against fanaticism, not could realize it never. The pedagogic work more important philosophical production of Varela, because fundamentally it served as the basis for the teachings of that matter in Cuba and other countries in Latin America until 1842, is their philosophy lessons.
Varela started in 1818 with a loose philosophical publications entitled preliminary lesson, aimed at students who this year began his course. The preliminary lesson in 1818 is the preamble to the lessons in philosophy, together with philosophical notes, also published in that year. The latter constitute the first Treaty of those containing the philosophy lessons.