Summary: Basing themselves on the fact that Francis of Assisi dictated a major portion of his Opuscula, Fr. K. Esser and other scholars had put forward the hypothesis that Francis probably dictated his simple “thoughts” in the vulgar idiom and left it to his copyists to develop them into a written form. This hypothesis, however, has been challenged by recent scholarly opinions. Studies on the autographs of Francis (A. Bartoli Langeli) have shown that Francis knew Latin better than has been generally accepted. Besides, an examination of the lexical concordances (Luvain, 1976) demonstrates that the Opuscula respect, without exception, the evangelical usus loquendi which the biographical sources speak about : that the titles honus, pater, magister should be given to God alone; that meus or other possessives should not be used with regard to material goods; that laus and its derivates should be attributed to God alone (cumulatively, 1043 occurrences). The conclusion is that Francis did not just dictate his “thoughts” but he also exercised a strict control on the language in which they were expressed.