Having studied at the Ecole des Beaux-Arts in his native Geneva, Lejeune moved to Paris in 1907 where he rented a studio at 6 rue Huyghens in Montparnasse. The studio, which came to be known as the Lyre et Palette, was a celebrated meeting place of artists and musicians of the period: amongst regular visitors were Modigliani, Apollinaire, Blaise Cendrars, Soutine, Picasso, Kisling, Max Jacob and Pierre Reverdy