Mexican Positivists undoubtedly enjoyed access to Spencer's publications albeit in a fragmented way, primarily through secondhand sources, of which the most important were the long-established French journal Revue des Deux Mondes and, also from France, the Revue Philosophique de la France et de l'Etranger, founded in 1876 by Théodule Ribot, with analysts such as Paul Janet and Emile-Honoré Cazelles as collaborators. Despite the limited proficiency of some of them in the English language, Mexican intellectuals complemented these French sources with the reading of brief notes from American journals and later Spanish translations, which, in view of the impossibility of adopting Spencer's ideas as a unified philosophy, were adapted by them to suit their particular circumstances, along with a variety of other ideas received from abroad. In the case of Bulnes, it is clear that he read something about Spencer because he mentioned him sporadically in his writings, together with Darwin and other fashionable scientists, philosophers, and sociologists, such as Taine. He wrote:

In fact, Bulnes had no problem in making it clear that he took the ideas in this document from the French book L'Evolution de la Morale, by Charles Jean-Marie Letorneau, who, for his part, had cited Spencer. As can be seen in the same quotation, Bulnes also referred to another of Letorneau's books, L'Evolution de la Morale: Leçons Profesées Pendant l'Hiver de 1885–1886, published in Paris in 1894 and later translated into English for publication in the United States. So, the obvious conclusion to draw in this instance is that Bulnes adopted Letorneau's ideas about Spencer, rather than reading Spencer's original works.

In another document Bulnes reproduced a series of quotations from Gustave le Bon, the anti-democratic French supporter of the veracity of science, who expressed in his political philosophy radical views against the ‘power of the multitudes’ and, as he believed, the inevitable incapacity of inferior people to learn.