An illustration from Jouffret's Traité élémentaire de géométrie à quatre dimensions
. The book, which influenced Picasso, was given to him by Princet.
Esprit Jouffret (1837 - 1904) was a French artillery officer, insurance actuary and mathematician, author of Traité élémentaire de géométrie à quatre dimensions (Elementary Treatise on the Geometry of Four Dimensions, 1903), a popularization of Henri 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.
Maurice Princet brought Traite to Picasso's attention. Picasso's sketchbooks for Les Demoiselles d'Avignon illustrate Jouffret's influence on the artist's work.