The varia lectio of medieval literary works is not only the direct trace of a sequence of modifications that the manuscript has undergone for more or less objective reasons, it bears also witness to the different paths that the auctoritas can follow. To identify among the multitude of variants that sometimes enrich the original text-originating from its different interpretations or executions-the mere errors to be corrected, the gaps to be reduced, the anachronisms to be banished, the lectiones faciliores whose trivialization deserves to be recognized and amended: all this is a philological task that should not be separated from the hermeneutical act that it implies.The necessary quest for the original lesson and even more for the lectio difficilior, which exalts the work of the philologist, thus able to identify the work of anastylosis of yesteryear's copyists, has sometimes lost sight of all that lectio facilior reveals us about the circulation and the reception of a text, a word, an expression. The present reflection seeks to explore the richness that errors can reveal to the hermeneut. Like Victor Hugo praising great scholars, the philologist could also exclaim: « Ô erreurs erreurs sacrées, mères lentes, aveugles et saintes de la vérité » ('O sacred errors, slow, blind and blessed mothers of the truth…').