This publication comprises the 170 letters written by the Abbe Dominique Chaix to Dr Dominique Villars between 1772 and 1799, when they were collaborating on the publication of the first flora for the old province of Dauphine. The letters reveal the uncertainties of plant classification in the late-18th century, but, more generally, the penetration of the Enlightenment into a remote, alpine region of France.