When Dr. Romana Guarnieri, in a letter to Osservatore Romano (16 June 1946), announced her discovery that Margaret Porette (d. 1 June 1310) was the author of The Mirror of Simple Souls, certainly a major French document of pre-Reformation spirituality, a sensation was created in the academic world. Although The Mirror is one of the few heretical documents to have survived the Middle Ages in its entirety, both its title and its authorship were among the most persistent and troublesome problems of scholarly research in the field of medieval vernacular languages. The Mirror, in its original French, survives only in the fifteenth-century manuscript which the great Cond