ROUSSEAU (Jean-Jacques). Letters written from the mountain. Amsterdam, Marc Michel Rey, 1764. 2 volumes in one in-8, porphyry calf, triple gilt fillet, smooth spine decorated, marbled edges (Binding of the period). First edition of Rousseau's last work published during his lifetime, in response to Lettres écrites de la campagne by Jean-Robert Tronchin, Attorney General of Geneva. "For the first time, the philosopher intervenes directly in the affairs of Geneva. [His letters] contain, beyond the constitutional subject, developments on the spirit of the Reformation, as well as a defence of the Social Contract". (Société J.-J. Rousseau). This edition is identical to the one described by Dufour under no. 232, except that the title does not contain the words En deux parties (In two parts), but Première et Seconde partie (First and second parts). It includes two errata, listing six and nine errors respectively (which are not corrected in the body of the text); four boxes on pp. 19, 77, 135 and 167 of the first part; and a 2-page extract from the publisher's catalogue. The author's motto is etched on the titles within a wreath of oak leaves. A very fine copy, with wide margins, in an attractive contemporary binding. Head joint slightly rubbed. Dufour, n°232 (another edition) - Gagnebin, n°1 - Rivoire, n°784.