princet is credited with introducing the work of henri poincaré and the concept of the "fourth dimension" to the cubists at the bateau-lavoir. princet brought to picasso's attention a 1903 book by esprit jouffret, "traité élémentaire de géométrie à quatre dimensions" ("elementary treatise on the geometry of four dimensions"), a popularization of poincaré's "science and hypothesis" in which jouffret described hypercubes and other complex polyhedra in four dimensions and projected them onto the two-dimensional page. picasso's sketchbooks for "les demoiselles d'avignon" illustrate jouffret's influence on the artist's work.