I began to draw from plant life and found the flat leaf forms were easier to do than thighs and breasts. I wanted to flatten. The plant drawings from that time until now have always been linear. They are exact observations of the form of the leaf or flower of fruit seen. Nothing is changed or added, no surface marking. They are not an approximation of the thing seen nor are they a personal expression or an abstraction. They are an impersonal observation of the form. When I applied the procedure to other things such as the vaulting of Notre Dame [church in Paris] or a patch of tar on the road, the subject of the drawings and the subsequent paintings were not recognizable even though they were exact copies of the thing seen. I wanted to use things that had no pictorial use.