Treat nature in terms of the cylinder, the sphere, and the cone, the whole put into perspective so that each side of an object, or of a plane, leads towards a central point. Lines parallel to the horizon give breadth, whether a sections of nature, or, if you prefer, of the spectacle which Pater omnipotens aeterne Deus unfolds before your eyes. Lines perpendicular to this horizon give depth... Everything I am telling you [ Joachim Gasquet ] about - the sphere, the cone, cylinder, concave shadow – on mornings when I'm tired these notions of mine get me going, they stimulate me, I soon forget them once I start using my eyes.