Foscolo intervened on questions regarding the Italian language with important theoretical considerations, many contained in the Pavia lectures, and also built a catalogue of minute observations on specific aspects of the Italian language via numerous interventions made in translations, comments and various discourses. The most conspicuous body of interventions date back to the English period, when the writer gave 14 lectures on the Italian language to paying participants between May and June 1823. The text of the first four lectures form the introductory discourse Principles of poetical criticism as applicable, more especially to Italian literature, the second lecture Origin and vicissitudes of the Italian language and two parts of Epoche della lingua italiana (Ages of the Italian language) on the years 1180-1280 were published in the “European Review” of 1824, while only parts of the other discourses remain. Reflections on the language were also contained in Epistolario and in Discorso storico sul testo del Decameron.

Foscolo's interest is directed primarily at the historical dimension of the language, one of the founding elements of national identity: "The history of peoples cannot be known unless by means of their language, nor does any language let itself be traced if not by means of history" ("La storia de’ popoli non può conoscersi se non per mezzo della loro lingua, né lingua veruna si lascia mai rintracciare se non per mezzo della Storia", Epoche della lingua italiana EN, XI, 1, p. 134). The critic started from the language's origins in Epoche della lingua italiana and, while considering only literary language, raised the problem of the dislocation between the written-literary national language and civil society, which only used dialect to communicate. Faithful to this conception of the language as an  intensely powerful agent of identity and hostile to any legislative excesses, he took up a moderate positive within the contemporary debate which matched that of the "classicists" and distanced himself both from the "neologists", who accepted foreign words and rejected the nation's history, and from the purists who rejected the innovations of that age and preferred the forms of the past. Besides, Foscolo was perfectly aware of the fact that the problem of the language would not have a proper solution without the political unity of the country.