Un été à la campagne: correspondance de deux jeunes parisiennes, recueillie par un auteur à la mode (A Summer in the Countryside: The Correspondence of Two Young Parisiennes, Collected by a Fashionable Author) is little more than a vehicle for a commissioned series of illustrations featuring naked young women, but it does show clearly how Barret had segued easily into the style of the 1960s.
The text is by Antoine Gustave Droz (1832–95), artist and author best known for his series of sketches of the intimacies of family life, published in the La Vie Parisienne and issued in book form in 1866 as Monsieur, Madame et Bébé. He was an early advocate of marriage as an equal partnership, and intimacy as an integral aspect of a truly loving relationship. He urged women to follow their hearts and marry a man of their own age: ‘A husband who is stately and a little bald is all right, but a young husband who loves you and drinks out of your glass without ceremony is better. Let him, if he ruffles your dress a little and places a kiss on your neck as he passes. Let him, if he undresses you after the ball, laughing like a fool. You have fine spiritual qualities, it is true, but your body is not bad either, and when one loves, one loves completely.’
In 1901 a private press English translation of Un été à la campagne was published in Paris, which you can read here, and an online French text can be found here.
The Barret-illustrated version of Un été à la campagne was published by Jacques Haumont in a limited numbered edition of 471 copies.