This is the fourth of five volumes of the letters of the French philosopher Claude Adrien Helvétius (1715-1771), author of the controversial De l'Esprit (1758). Featuring the correspondence of Mme Helvétius, née Anne Catherine de Ligniville (1722-1800), in the years following her husband's death, this volume also includes letters by and to Helvétius discovered since the publication of the first three volumes.Mme Helvétius enjoyed an active widowhood, welcoming to her salon...