Even though the Revista de Portugal project had failed and publication of the Suplemento Literário da Gazeta de Notícias had been short-lived, Eça still did not abandon the idea of designing and editing another periodical, this time in partnership with Alberto de Oliveira.

To write about a magazine of which so little is known, of which only the draft outlines of a few issues exist and which never actually materialized is an interesting exercise. There are only eight known letters among Eça's correspondence on the subject, most of which were written to Alberto de Oliveira. Although useful, as they provide some details regarding the genesis of the new publication, these letters on their own are not enough to reconstruct the profile of ‘O Serão’.

However, Eça's literary archive at the Portuguese National Library in Lisbon holds several important documents that illustrate what the magazine might have been like. Among these are the detailed plan for the first six issues, together with a list of tasks that were to be Eça's responsibility (E1/276) and a list of possible collaborators (E1/277). Although the former was written by Alberto de Oliveira and not by Eça, as the handwriting indicates, the inspiration behind it was undoubtedly Eça's, as his correspondence shows.

In a letter dated 10 November 1894, Eça warns Alberto de Oliveira: ‘it is necessary to have at least four or six issues studied, guaranteed, already partly collated.