The new edition of Montesquieu’s letters, with those from 1700-1728 available in open access (Montesquieu. Bibliothèque & éditions, http://montesquieu.huma-num.fr), reveals a number of hitherto unknown facts. In particular, it sheds new light on the publication, in 1726, of Mme de Lambert’s Avis d’une mère à son fils (or Lettre sur la vraie gloire). This project engaged Montesquieu but also two of his intimate friends: Jean-Jacques Bel, in Bordeaux, and the Oratorian Desmolets, in Paris. These relationships now help us to better understand his activity during this decisive year, in which he renounced his position as Président à mortier at the Parlement de Bordeaux and became a major personality in the Parisian literary milieu.