Preston Blier says that, like Gauguin and several other artists in this era, Picasso used illustrated books for many of his preliminary studies for this painting. In addition to the Frobenius book, his sources included a 1906 publication of a twelfth-century Medieval art manuscript on architectural sculpture by Villiard de Honnecourt and a book by Carl Heinrich Stratz of pseudo-pornography showing photos and drawings of women from around the world organized to evoke ideas of human origins and evolution. Blier suggests that this helps account for the diversity of styles Picasso employed in his image-filled sketchbooks for this painting. These books, and other sources such as cartoons, Blier writes, also offer hints as to the larger meaning of this painting. Mathematics Maurice Princet, a French mathematician and actuary, played a role in the birth of Cubism as an associate of Pablo Picasso, Guillaume Apollinaire, Max Jacob, Jean Metzinger, Robert Delaunay, Juan Gris and later Marcel Duchamp. Princet became known as "le mathématicien du cubisme" ("the mathematician of cubism"). Princet is credited with introducing the work of Henri Poincaré and the concept of the "fourth dimension" to artists at the Bateau-Lavoir. Princet brought to the attention of Picasso, Metzinger and others, a book by Esprit Jouffret, Traité élémentaire de géométrie à quatre dimensions (Elementary Treatise on the Geometry of Four Dimensions, 1903), 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 surface. Picasso's sketchbooks for Les Demoiselles d'Avignon illustrate Jouffret's influence on the artist's work. Impact Although Les Demoiselles had an enormous and profound influence on modern art, its impact was not immediate, and the painting stayed in Picasso's studio for many years. At first, only Picasso's intimate circle of artists, dealers, collectors and friends were aware of the work. Soon after the late summer of 1907, Picasso and his long-time lover Fernande Olivier (1881–1966) had a parting of the ways. The re-painting of the two heads on the far right of Les Demoiselles fueled speculation that it was an indication of the split between Picasso and Olivier. Although they later reunited for a period, the relationship ended in 1912. A photograph of the Les Demoiselles was first published in an article by Gelett Burgess entitled "The Wild Men of Paris, Matisse, Picasso and Les Fauves", The Architectural Record, May 1910. Les Demoiselles would not