Marianna Alcoforado (1640-1723), alleged author. Some says that the true author is Gabriel-Joseph de Lavergne, Earl of Gijerag, friend of Nicolas Boileau’s and Jean Racine’s.
Myriam Cyr, in her book published in 2006, “Letters of the Portuguese nun: discovery and mystery of a secret love of the XVII century,” argues that Mariana Alcoforado really existed and that there was an educated nun, who knew how to write and that can be considered the author of these five famous letters.