volumes to convey the solidity and structure of objects. Their weight, placement and effects upon each other, and the inseparability of form and color, was one of the principal lessons of Cézanne. Forms were simplified and distorted, each shape and color modified by another, rather than splintered. His concern was to establish weight, density and volumetric relationships among sections of a broad subject. Gleizes himself characterized the 1910–11 phase of his work as an "analysis of volume relationships," though it bears little relation to the traditional use of the word "analytical" in our understanding of Cubism. "We laugh out loud when we think of all the novices who expiate their literal understanding of the remarks of a cubist and their faith in absolute truth by laboriously placing side by side the six faces of a cube and both ears of a model seen in profile." (Albert Gleizes, Jean Metzinger) A central theme of Du "Cubisme" was that access to the true essence of the world could be gained by sensations alone. The sensation offered by classical painting was very limited: to only one point of view, from a single point in space and frozen in time. But the real world is mobile, both spatially and temporally. Classical perspective and the formulations of Euclidean geometry were only conventions (to use Poincaré's term) that distance us from the truth of our sensations, from the truth of our own human nature. Man sees the world of natural phenomena from a multitude of angles that form a continuum of sensations in perpetual and continuous change. The Cubists' aim was to completely eschew absolute space and time in favor of relative motion, to grasp through sensory appearances and translate onto a flat canvas the dynamical properties of the four-dimensional manifold (the natural world). Only then could one achieve a better representation of the mobile reality of our living experience. If Gleizes and Metzinger write in Du "Cubisme" that we can only know our sensations, it is not because they wish to disregard them, but, on the contrary, to understand them more deeply as the primary source for their own work. In reasoning this way, Gleizes and Metzinger demonstrate that they are successors to Cézanne, who insists that everything must be learnt from nature: "Nature seen and nature felt... both of which must unite in order to endure." 1913–1918 In February 1913, Gleizes and other artists