The corpus of Foscolo's letters is large and a fundamental source for the reconstruction of the affairs of his tormented life and the writing process, often equally tormented, of many works (such as Le Grazie).
The Epistolario takes up six volumes of the Edizione Nazionale of Opere (Works) by Foscolo, and includes letters written from 1794 up to his death; the number of letters sent to Foscolo from his many interlocutors, on the other hand, is not very high.
Research into the documents started immediately after the poet's death. The biggest collections of letters are conserved at the Biblioteca Nazionale (National Library) of Florence and at Livorno's Biblioteca Labronica (Labronica Library), but each letter has its won story and many are spread around various archives and libraries. The task of collecting the letters sent to Foscolo, many of which were scattered while the writer was still alive, is even more difficult: part of his documents, for example, were collected in the chest entrusted to Silvio Pellico when the writer left Milan for exile in 1815 and were lost after changing hands many times.
Some groups of letters sent to a specific receiver form separate blocks in themselves: this is seen, for example, in the letters to Antonietta Fagnani Arese, where the prose is a sort of literary apprenticeship and is undoubtedly linked to that writing produced at the same time in Ortis. Many letters to significant interlocutors (for example, the group of Florentine friends from "Antologia" or Vincenzo Monti) contain important reflections and news useful for the reconstruction of the writer's poetry and for the formation of a better picture of his critical thought.