|VII: Paris After 1945|
After the liberation of Paris, Lahner returned immediately to the rue des Périchaux and earned a living for a while supplying newspaper and magazine illustrations. He also illustrated books: Noëls du monde ; Claude Aveline's L'Oiseau qui n'existe pas ; and a book of poems by Marcel Sauvage entitled Poèmes en prose , which include the charming Les Puces (fig.29). Like the majority of Parisians whose social activities had been severely curtailed during the war, he enthusiastically took to the streets once again, frequenting old haunts and becoming an habitué of the cafés of the artistic and literary intelligentsia. He made daily visits to the Flore in Saint-Germain-des-Près where he encountered people like Sauvage, Jean-Paul Sartre, Simone de Beauvoir, Boris Vian, Jacques Prévert;, Simone Signoret, Yves Montand, Juliette Greco, and Jean-Louis Barrault. During this period he painted portraits of Greco and Montand. From 1946 he also began to paint more and to exhibit his paintings. As a surviving member of the previous generation and the now defunct École de Paris, Lahner suddenly found himself in the enviable position of an "old master." His works were lavishly praised in the press and increasingly sought out by collectors.
Much of Lahner's new-found popularity can be credited to the persistent devotion and promotional efforts of his old friend Géo-Charles. In l945 the poet-critic was in Budapest where he gave a talk on Lahner.  He followed this up with a number of substantial articles on the painter in journals and in the popular press. In Géo-Charles' estimation, "Lahner was knowledgeable enough to avoid the two great errors of painting in our times: abstract art...and Surrealism." Instead, his art is characterized by "poésie," which according to Geo-Charles drew freely on Oriental art, Hungarian folk art, and Persian poetry for its inspiration.  Some of the same themes are reiterated in an article of that year by Jean Bouret, another critic instrumental in Lahner's career:
Much too fond of the sculptural forms of the body, he refuses (to adopt) Cubist and post-Cubist deformation, his only preoccupation is to poeticize his subject to the utmost.
It is characteristic of these critics that, when Lahner did begin painting non-representational subjects, they followed this new direction in his work, at first with reserve, then with committed enthusiasm. Marcel Sauvage perhaps best described the general feeling toward Lahner: "bon pied, bon oeil." 
In the post-war era Lahner demonstrated a renewed
commitment to the painting of landscape and of female subjects. Gradually,
however, he expanded this limited iconography to include religious or
quasi-religious subjects executed in a manner imitative of stained glass.
Lahner also renewed his interest in caves. These interests were fueled
by the widespread dissemination of discoveries related to cave paintings
in the Dordogne, areas he had visited during and immediately after the
war. A small number of paintings record Lahner's interest in cave painting
and a fascination for the cosmology invented by primitive man. Finally,
there are the abstract works that he began painting regularly by l950.
The buoyant, experimental handling of these abstract subjects contrasts
markedly with the cool, detached manner of his representational pictures.
Once free from the subject and the precarious balance it requires between
surface pattern and illusionism, Lahner allowed himself a free reign in
devising decorative and often playful constructions.